P-dog's blog: boring but important: 201103

20110331

Physics midterm problem: out-of-phase source interference

Physics 205B Midterm 1, spring semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problems 25.1, 25.3

[20 points.] A radio transmitter sends a signal of wavelength 0.18 km to a receiver 1.22 km away.  The signal also travels to the receiver by another path where it reflects with a 180° phase shift from a metal skyscraper, as shown at right. As a result, there is a destructive signal at the receiver. Find the shortest possible distance between the skyscraper and the receiver. Show your work and explain your reasoning.

Solution and grading rubric:

p = 20/20:
Correct. Sets up proper destructive interference condition for out-of-phase sources (∆l = m·λ), where ∆l = (1.30 km - x) - 1.22 km, and solves for x, the distance from the skyscraper to the receiver using m = 1 to obtain the shortest possible skyscraper-receiver distance.
r = 16/20:
Nearly correct, but includes minor math errors.
t = 12/20:
Nearly correct, but approach has conceptual errors, and/or major/compounded math errors.
v = 8/20:
Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner.
x = 4/20:
Implementation of ideas, but credit given for effort rather than merit.
y = 2/20:
Irrelevant discussion/effectively blank.
z = 0/20:
Blank.

Grading distribution:
Section 30882
Exam code: midterm01g74S
p: 2 students
r: 0 students
t: 4 students
v: 0 students
x: 2 students
y: 0 students
z: 0 students

A sample "p" response (from student 2414):

Physics midterm problem: bifocal prescription

Physics 205B Midterm 1, spring semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 24.24

"Image of an eyeglass prescription"
Dpbsmith
 http://en.wikipedia.org/wiki/File:Specrx-prescription2.jpg

Shown above is an (edited) copy of an eyeglass prescription, where the far and near corrective optics are prescribed to be –3.25 diopters and +2.00 diopters, respectively, for the right and left eyes. Determine (a) the uncorrected far point for the right eye, and (b) the uncorrected near point for the left eye of this patient. (Neglect the distance between these glasses and eyes.) Show your and explain your reasoning using properties of lenses and vision.

Solution and grading rubric:

p:
Correct. Uses the thin lens equation 1/p + 1/q = 1/f = P, where p is the far point F or near point N, and q = –∞ or –0.25 m, respectively, and solves for F and N. Minor negative sign errors okay.
r:
Nearly correct, but includes minor math errors.
t:
Nearly correct, but approach has conceptual errors, and/or major/compounded math errors. Applies F = –1/D correctly to find far point, but incorrectly applies N = 1/P to find near point; or may use N = 1/(P – 1/(0.25 m)) correctly to find near point, but incorrectly applies it to find the far point.
v:
Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner.
x:
Implementation of ideas, but credit given for effort rather than merit.
y:
Irrelevant discussion/effectively blank.
z:
Blank.

Grading distribution:
Section 30882
Exam code: midterm01g74S
p: 1 student
r: 0 students
t: 7 students
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 2180) with a relatively minor sign error:

20110330

Physics midterm question: three-layer refraction

Physics 205B Midterm 1, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Comprehensive Problem 23.97

[10 points.] A beam of light strikes an air-oil interface with an incident angle of 41°. The beam travels through the oil and emerges from a parallel oil-glass interface below. Ignore reflections, and this diagram is not drawn to scale.  Is the angle of the exiting ray in glass greater than, less than, or equal to 41°? Explain your reasoning using the properties of light and refraction.

Solution and grading rubric:

p = 10/10:
Correct. Solves for theta_3 after first solving for theta_2 using Snell's law twice; or solves for theta_3 by noting that the oil layer can be ignored mathematically in n_1*sin(theta_1) = n_3*sin(theta_3); or argues that since the indices of refraction increase, the angles will decrease such that theta_3 > (theta_2) > theta_1.
r = 8/10:
As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes.
t = 6/10:
Nearly correct, but argument has conceptual errors, or is incomplete.
v = 4/10:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner.
x = 2/10:
Implementation/application of ideas, but credit given for effort rather than merit.
y = 1/10:
Irrelevant discussion/effectively blank.
z = 0/10:
Blank.

Grading distribution:
Section 30882
Exam code: midterm01g74S
p: 8 students
r: 0 students
t: 0 students
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 7503), eliminating n_2*sin(theta_2) in the two Snell's law equations:

A sample "p" response (from student 3373), explicitly solving for theta_2, and then for theta_3:

A sample "p" response (from student 1990), arguing qualitatively for theta 1 > theta_2 > theta_3:

Physics midterm question: electric potential energy of two charges

Physics 205B Midterm 1, spring semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problems 17.1, 17.4

A +5.0 nC charge is held at the origin, and a –2.5 nC charge that can be moved horizontally along the x-axis is initially placed at x = +2.0 cm. In order to increase the electric potential energy of the –2.5 nC charge, should it be moved to the left, to the right, or would this not be possible? Explain your reasoning by using the properties of charges and electric potential energy.

Solution and grading rubric:

p:
Correct. The two charges attract each other, such that the the –2.5 nC charge will experience an electric force to the left. In order to increase its potential energy, to do work on this charge would require pulling it to the right. Makes a qualitiative argument, or demonstrates this quantitatively by plugging in numbers or argues that increasing r will make EPE = k·(+5.0×10^–9 C)·(–2.5×10^–9 C)/r a smaller negative number, thus increasing EPE.
r:
As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes.
t:
Nearly correct, but argument has conceptual errors, or is incomplete.
v:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner.
x:
Implementation/application of ideas, but credit given for effort rather than merit.
y:
Irrelevant discussion/effectively blank.
z:
Blank.

Grading distribution:
Section 30882
Exam code: midterm01g74S
p: 7 students
r: 1 student
t: 0 students
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 9904) with qualitative argument based on doing work on charges to increase electric potential energy:

A sample "p" response (from student 7974), explicitly calculating the initial and final electric potential energies (without nC to 10^–9 C conversions, but okay for determining the relative change in electric potential energy):

20110329

Overheard: Horsehead Nebula dementor

Astronomy 210, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

The_Horshead_Nebula [sic]
http://commons.wikimedia.org/wiki/File:The_Horshead_Nebula.jpg
Originally uploaded by the European Southern Observatory

(Overheard during slide presentation on emission/reflection/dark nebulae, with slide of Barnard 33 (Horsehead Nebula) on-screen.)

Instructor: "Just like when you look at clouds overhead, astronomers love to look at nebulae in space, and ask themselves, 'Okay, what does that look like?'" (Turning around and gesturing towards slide of Barnard 33) "So, what does this nebula look like to you?"

(Beat.)

Student: "Like a dementor--from Harry Potter!"

20110328

Astronomy quiz archive: sun/spectra/star properties

Astronomy 210 Quiz 4, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

Section 30674, version 1
Exam code: quiz04nK4n

Section 30674

Quiz 4 results (max score = 40):
   0- 8.0 : *  [low = 2.5]
 8.5-16.0 : ******
16.5-24.0 : *************  [mean = 23.1 +/- 7.3]
24.5-32.0 : *************
32.5-40.0 : ****  [high = 40.0]

Section 30676, version 1
Exam code: quiz04s0sO

Section 30676

Quiz 4 results (max score = 40):
   0- 8.0 : *  [low = 5.0]
 8.5-16.0 : ***********
16.5-24.0 : ****************  [mean = 20.5 +/- 7.8]
24.5-32.0 : ******
32.5-40.0 : *******  [high = 40.0]

20110327

Astronomy quiz question: same luminosity giant and main sequence star

Astronomy 210 Quiz 4, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

A giant star has the same luminosity as a main sequence star. As the giant is larger, it will have a __________ than the main sequence star.
(A) cooler temperature.
(B) hotter temperature.
(C) smaller parallax angle.
(D) larger parallax angle.

Correct answer: (A)

The Stefan-Boltzmann law states that luminosity is proportional to size (that is, surface area) and temperature (T^4). Since these two stars have the same luminousity, then the larger star must be cooler than the smaller star.

Section 30674
(A) : 29 students
(B) : 4 students
(C) : 2 students
(D) : 4 students

"Success level": 78% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.60
Exam code: quiz04nK4n

20110326

Astronomy quiz question: star locations

Astronomy 210 Quiz 4, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

How far away are Star X and Star Y located from Earth?
(A) Both stars are closer than 10 parsecs.
(B) Both stars are farther than 10 parsecs.
(C) Star X is closer than 10 parsecs,  Star Y is farther than 10 parsecs.
(D) Star X is farther than 10 parsecs,  Star Y is closer than 10 parsecs.

Correct answer: (A)

For Star X, its apparent magnitude of -1.0 is brighter than its absolute visual magnitude of 0.0. For Star Y, its apparent magnitude of 0.0 is also brighter than its absolute visual magnitude of +1.0. Both stars appear bright as seen from Earth, at their positions, and since conceptually bringing them to the "fair distance" of 10 parsecs would make them both dimmer, they must be located closer than 10 parsecs away from Earth.

Section 30676
(A) : 18 students
(B) : 2 students
(C) : 11 students
(D) : 10 students

"Success level": 48% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.45
Exam code: quiz04s0sO

20110325

Astronomy current events question: dark energy theory revision

Astronomy 210L, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)

Clara Moskowitz, "Bizarre Dark Energy Theory Gets Boost From New Measurements," March 15, 2011
http://news.yahoo.com/s/space/20110315/sc_space/bizarredarkenergytheorygetsboostfromnewmeasurements

The Wide Field Camera 3 on the Hubble Space Telescope observed __________, in order to revise theories of dark energy.
(A) type Ia supernova explosions.
(B) rapid protostar formation.
(C) distances to nearby stars.
(D) galaxy collisions.
(E) very old globular clusters.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 9 students
(B) : 8 students
(C) : 7 students
(D) : 1 student
(E) : 0 students

Astronomy current events question: MESSENGER orbiting Mercury

Mike Wall, "NASA Probe Becomes First Spacecraft to Orbit Mercury," March 17, 2011
http://www.space.com/11160-nasa-spacecraft-mercury-orbit-messenger.html

On March 17, NASA's Messenger spacecraft fired its main thruster in order to:
(A) catch up to dock with a fueling station.
(B) slow down to begin orbiting Mercury.
(C) avoid collision with an asteroid.
(D) boost its orbit away from a solar flare.
(E) reach the opposite side of the sun.

Correct answer: (B)

Student responses
Sections 30678, 30679, 30680
(A) : 0 students
(B) : 37 students
(C) : 5 students
(D) : 5 students
(E) : 2 students

Astronomy current events question: Sendai earthquake effects

Alan Buis, "Japan Quake May Have Shortened Earth Days, Moved Axis," March 14, 2011
http://www.nasa.gov/topics/earth/features/japanquake/earth20110314.html

The Sendai earthquake in Japan may have shortened the length of Earth's day, and shifted its axis, according to:
(A) worldwide mismatches of atomic clocks.
(B) the sudden closeness of the moon's distance.
(C) the early start of daylight savings time.
(D) theoretical calculations.
(E) GPS data errors.

Correct answer: (D)

Student responses
Sections 30678, 30679, 30680
(A) : 3 students
(B) : 7 students
(C) : 0 students
(D) : 38 students
(E) : 3 students

Astronomy current events question: Titan methane rains

Jia-Rui C. Cook, Joe Mason, Michael Buckley, "Cassini Sees Seasonal Rains Transform Titan's Surface," March 17, 2011
http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20110317.html

NASA's Cassini spacecraft observed __________ on Saturn's moon, Titan, which may be evidence of seasonal methane rains.
(A) darkening of certain areas.
(B) shifting methane icebergs.
(C) the Cassini-Huygens lander floating.
(D) widespread lichen-like growths.
(E) rapid erosion of rock formations.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 18 students
(B) : 3 students
(C) : 1 student
(D) : 1 student
(E) : 3 students

20110324

Astronomy quiz question: hottest star

Astronomy 210 Quiz 4, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

Which star is hottest?
(A) B5 supergiant.
(B) K2 supergiant.
(C) M2 giant.
(D) O5 main sequence star.

Correct answer: (D)

Using the OBAFGKM spectral type mnemonic, or reading off of an H-R diagram (provided on this quiz), the O5 main sequence star is the hottest, followed by the B5 supergiant, K2 supergiant, and M2 giant. Possibly a few students chose the B5 supergiant "B is for blue-hot" (when in fact the O5 main sequence star would be hotter). Notably, this quiz was given the week after an OBAFGKM poetry slam.

Section 30676
(A) : 7 students
(B) : 5 students
(C) : 1 student
(D) : 28 students

"Success level": 70% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.73
Exam code: quiz04s0sO

20110323

Astronomy quiz question: same-size giant and supergiant

Astronomy 210 Quiz 4, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

A supergiant has the same size as a giant. As the supergiant is more luminous, it will have a __________ than the giant.
(A) cooler temperature.
(B) hotter temperature.
(C) larger parallax angle.
(D) smaller parallax angle.

Correct answer: (B)

The Stefan-Boltzmann law states that luminosity is proportional to size (that is, surface area) and temperature (T^4). Since these two stars have the same size, then the more luminous star must be hotter than the less luminous star.

Section 30676
(A) : 2 students
(B) : 33 students
(C) : 3 students
(D) : 0 students

"Success level": 81% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.27
Exam code: quiz04s0sO

20110322

Astronomy quiz question: stars moving away from/toward Earth

Astronomy 210 Quiz 4, spring semester 2011
Cuesta College, San Luis Obispo, CA

[Version 1]
Stars moving away from Earth have:
(A) very small parallax angles.
(B) very large parallax angles.
(C) red-shifted absorption lines.
(D) blue-shifted absorption lines.

Correct answer: (C)

Light from a star moving away from Earth would have wavelengths stretched out because of the Doppler shift, which would shift absorption lines towards slightly larger values ("red-shifted").

Section 30674
(A) : 10 students
(B) : 6 students
(C) : 20 students
(D) : 1 student
(No response) : 1 student

"Success level": 50% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.96
Exam code: quiz04nK4n

[Version 2]
Stars moving toward Earth have:
(A) very small parallax angles.
(B) very large parallax angles.
(C) red-shifted absorption lines.
(D) blue-shifted absorption lines.

Correct answer: (D)

Light from a star moving towards Earth would have wavelengths scrunched up because of the Doppler shift, which would shift absorption lines towards slightly smaller values ("blue-shifted").

Section 30676
(A) : 4 students
(B) : 10 students
(C) : 8 students
(D) : 19 students

"Success level": 49% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.82
Exam code: quiz04s0sO

20110321

Education research: partial credit for multiple-choice questions (PCMC) student attitudes (Spring semester 2011)

Starting Fall semester 2008 and continuing through Spring semester 2011, Cuesta College students taking Astronomy 210 (introductory astronomy) at Cuesta College, San Luis Obispo, CA have piloted the use of partial credit for multiple-choice (PCMC) questions.

During the ninth week of instruction (after taking four multiple-choice question quizzes, and a midterm with multiple-choice questions and short-answer/essay questions), students were given the opportunity to evaluate PCMC in an online "Partial Credit for Multiple-Choice (PCMC) Survey" hosted by SurveyMonkey.com.

These are the complete survey results. Analysis will be forthcoming after more data has been compiled from future semesters. Values for the mean and standard deviations are given next to the modal response category for each question. Note that the order of questions within sections II and III were randomly scrambled for each student.

Partial Credit for Multiple-Choice Survey
Cuesta College
Astronomy 210 Spring Semester 2011 sections 30674, 30676
(N = 45)

I. In order to receive credit for completing this survey, 
   first enter your first and last name below:
   ____


II. Recall that for this semester there is PCMC = "partial 
    credit for multiple choice," where you can get partial 
    credit even after circling a wrong answer, if you have 
    also eliminated an incorrect answer by marking it with 
    an "x."      
      Answer the following statements which may or may not 
    describe your beliefs about PCMC in this class.      
      Because of PCMC...

II.1 ...I read questions more carefully.
1. Strongly disagree      0 : 
2. Disagree               2 : **
3. Neutral                6 : ******
4. Agree                 29 : *****************************  [4.2 +/- 0.8]
5. Strongly agree        20 : ********************
     
II.2 ...I spend more time taking a test. 
1. Strongly disagree      4 : ****
2. Disagree               6 : ******
3. Neutral               14 : **************
4. Agree                 21 : *********************  [3.5 +/- 1.1]
5. Strongly agree        11 : ***********

II.3 ...I feel more confident about circling a correct choice.
1. Strongly disagree      1 : *
2. Disagree               4 : ****
3. Neutral               11 : ***********
4. Agree                 24 : ************************  [3.9 +/- 1.0]
5. Strongly agree        16 : ****************

II.4 ...I look for incorrect choices before circling a correct choice.
1. Strongly disagree      1 : *
2. Disagree               9 : *********
3. Neutral                9 : *********
4. Agree                 17 : *****************
5. Strongly agree        20 : ********************  [3.8 +/- 1.1]

III. Answer the following statements which may or may not describe 
     your beliefs about PCMC in this class.  

III.1 PCMC helped me answer test questions better.
1. Strongly disagree      1 : *
2. Disagree               2 : **
3. Neutral               10 : **********
4. Agree                 23 : ***********************  [4.1 +/- 0.9]
5. Strongly agree        20 : ********************

III.2 I would recommend using PCMC in future semesters of this class.   
1. Strongly disagree      0 : 
2. Disagree               0 : 
3. Neutral                5 : *****
4. Agree                 17 : *****************
5. Strongly agree        34 : **********************************  [4.5 +/- 0.7]

III.3 Having PCMC a positive experience.
1. Strongly disagree      0 : 
2. Disagree               1 : *
3. Neutral                7 : *******
4. Agree                 22 : **********************
5. Strongly agree        27 : ***************************  [4.3 +/- 0.8]

III.4 Using PCMC was difficult.    
1. Strongly disagree     22 : **********************  [2.0 +/- 3.0]
2. Disagree              19 : *******************
3. Neutral               10 : **********
4. Agree                  4 : ****
5. Strongly agree         1 : *

III.5 I would identify incorrect choices even without PCMC.  
1. Strongly disagree      2 : **
2. Disagree               7 : *******
3. Neutral               20 : ********************
4. Agree                 22 : **********************  [3.4 +/- 1.0]
5. Strongly agree         5 : *****

IV. (Optional.)  Please type in any comments you may have regarding 
    the use of PCMC in this class.

The following are all of the student responses to this question, verbatim and unedited.

"I liked PCMC because it allows you to get points back. It helps your grade if you need it. =)"

"i like it except for when i go to look at my score i have a hard time understanding it ."

"I think that the PCMC is really great and think it is very effective in the class on tests and quizzes. The PCMC makes me more confident that I will not fail and at least get some points when I am going between two answers. I normally have really bad test anxiety and PCMC has really helped me not freak out as much as I normally would. I really like the use of PCMC in this class and really wish that more teachers would use this method."

":)"

"i was lost but being in a group with people that know it and got it helps"

"good"

"I think it is very helpful. I also think that it is great to have an extra opportunity to receive points when it could be just written off as wrong."

"Its useful but is doing things partially and getting partial credit really good if the student as clearly demonstrated they do not know the material? I suppose though that even those student will not be helped much by PCMC. I do believe it is excellent for those who can recall some details about the materials which does in fact demonstrate that they have learned some of the material, which i think should be rewarded with some credit, especially if some of the concepts are difficult to grasp."

":)"

"I like it."

"I really appreciate the opportunity to use the PCMC method on our tests. It encourages me to think about the question on a different level and provides me with the confidence to know that even if i didnt get an answer correct, I know my thought process will be recognized and appreciated."

"I think it is a great fall back for a student struggling with the test."

":)"

"I love that we can get partial credit for indentifying wrong answers, it makes me feel a little bit better if I didn't know the correct answer in the first place."

"It helps because I'm doing so poorly"

"I love it."

"it's good :)"

"It gives you hope on a question that you really have no idea how to answer."

"PCMC WOO!"

"I really like PCMC as a system for getting some partial credit on quizzes and tests. It makes it less stressful because even if I don't have certainty about my answer, I can be certain about at least one wrong answer."

"I think that instead of .5 points it should be anywhere between 1-1.5 points because if there is a 4 choice question, eliminating one question removes 25% of the choices so we should get at least 25% of the points because we knew what answer was wrong out of the 4 showing that we know what's going on.Kinda."

"It definitely helps :)"

"If we don't 'x' out an answer we know is wrong, will we not get as much credit?"

"I often confuse myself trying to figure out which wrong answer I should choose."

"It's a good method"

"i like the PCMC"

"I like it. Its just awesome"

"I feel like sometimes if i 'x' out a wrong answer then the question becomes incorrect and i am only graded solely on the partial credit wrong answer i 'x'ed out."

"I think PCMC is a great idea- however, I think it would help to have more review. I know time is a constraint, but it's hard to have a quiz or test almost every week and not go over "problem spots" or maybe have just 10 minutes the class after the quiz/test to go over common wrong answers. Even though it's nice to get some points made up with the PCMC, I think it would be better yet to know more of the correct answers. I say keep the PCMC and maybe add a 10 minute quiz or test review, or have a question on our Online Reading Assignments that allows us to ask for a review of certain topics."

"PCMC is a good help to figuring out the right answer easily"

"Gives a different perspective on the test. anybody would like to have that possibility to get a little credit when not being 100% that the selected answer was best while especially while mind dueling between two"

"I love it :)"

"I think it is really helpful. It helps you to narrow down your choices and get some extra points at the same time! I just wish they were worth a little more. Maybe a full point? .5 out of 4 isn't a whole lot, but every bit helps!"

"I think it's rad."

"Great tool. Helps you cancel out the wrong answer ."

"I like PCMC because sometimes you are torn between two answers... so if you cross off the ones you know are definitely incorrect, you already have a better score than if you took a chance and had to guess."

"Golden"

"helps"

"I think that this method is very effective for nervous multiple-choice test takers! I am definitely a fan."

"I really love all the oppurtunities we get in order to get more points inside class... PCMC really confuses me. Can you explain it more in detail?"

"PCMC has me going into stressfully test situations with more optimism and relaxation which leads to better scores"

":P"

"I think that there should be partial credit for x-ing out any of the incorrect answers not just the most incorrect because then I worry about that as well as circling the right answer. Then partial credit would be more effective and give students a few extra points if they are struggling with a few questions"

"LOVE PCMC!!!!!!!!!!!!!!!!"

"I like the PCMC because I don't feel doomed by an incorrect answer. My grade benefits as I am often able to use the knowledge I have obtained to eliminate an answer I know is wrong."

Education research: partial credit for multiple-choice questions (PCMC) student attitudes (Fall semester 2008)

Education research: partial credit for multiple-choice questions (PCMC) bibliography

20110320

Online reading assignment question: confusing Midterm 1 astronomy topics

Astronomy 210 Reading Assignment 7, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

110316-confusingwordle
http://www.flickr.com/photos/waiferx/5533436160/
Originally uploaded by Waifer X

Wordle.net tag cloud for confusing topics covered in Midterm 1, generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA (http://www.wordle.net/show/wrdl/3315166/Untitled).

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

List at least three words describing confusing subjects covered in class (up through this midterm). (Graded for completion.)

[Responses have been edited to consolidate related common subjects.]

Student responses
Sections 30674, 30676

telescopes, moonphases, moonrise, moonset, planetfinding
telescopes prograde retrograde
eclipses, light, magnitude
nothing
everything
quantummechanics, orbits rotation
hard, uninteresting confusing
moonphases
eclipses, photosphere, chromosphere, corona
astronomers history
moonphases, telescopes, eclipses
starwheel
spectra
moonphases
telescopes moonphases Sun
reddwarfs whitedwarfs luminosity electromagneticradiation
electromagneticradiation telescopes imagingsystems photometers
telescopes
retrograde, telescopes, starsizes
telescopes starwheel
everythingatfirst nothingafterlecture
difficult, thoughtproducing, vague
mindboggling, headache enigma
telescopes, Sun
astronomers, astrology
starwheel
photons
starpatterns moonphases Sun
moonphases, telescopes, astronomers
everything
eclipses, telescopes, planets
Dopplereffect, gammarays, quantummechanics
Idontknow
rotation, starwheel
ridiculous, hard, opposites
telescopes, prograde, zodiac
telescopes, eclipses
planetfinding
moonphases
tough extreme difficult
telescopes
revolution rotation telescopes Ptolemy
everything
Mayancalendar 2012
planetfinding
luminosity, mass, density
eclipses, umbra penumbra
star, planets, solarsystem
Sun, moonphases, constellations
eclipses orbits telescopes
moonrise moonset
everything
Moon, telescopes, eclipses
astronomers, Aristole, Kepler
planets
direction
Dopplereffect telescopes Moon
apparentmagnitude absolutemagnitude telescopes
telescopes Dopplereffect stars
Kepler, Galileo, Copernicus
telescopes, moonphases
moonphases moonrise moonset
telescopes
history astronomers laws
mixingthingsup
everything
quantummechanics
planetfinding

Describe your most confusing subject, and briefly explain why this subject confused you. (Graded for completion.)

The following are all of the student responses to this question, verbatim and unedited.

"The moon phases. The rising and setting was confusing."

"The telescope subject the confuses me because i do not understand the refections of the lights."

"The history of astronomy in chapter 2, because there are so many names and laws and I get them all confused."

"The reason any subject for me that was confusing is because I mixed things up, but I was sure to make sure I understood it properly before our quizzes."

"everything!"

"quantum leaps because i dont really unserstand how they relate to the subject."

"The most confusing subject for me is the planet positions, i can never seem to get them right."

"moons because of the setting and rising and adding and subtracting."

"I never really understood the eclipses. It didn't seem to be covered in much detail and it seemed like everyone else was a little bit confused but just because a few people got the flaschard questions right we moved on."

"The different people throughout history trying to keep track of what they did and the laws that each came up with was really confusing."

"The moon phases were by far the hardest part"

"I would have to pick the star chart for its complexity making it easy to make a mistake."

"absorption emission and continues spectras (just no idea what the truely actually are symbolizing, not enough explanation)"

"moon phases because i some times get mixed up"

"I think that I will have a hard time with the moon phases."

"The luminosity bar-graph just didn't make sense, I can get the correct answer without it, but when I try to use the graph it just doesn't work."

"the electromagnetic spectrum was confusing at first because I wasn't quite sure how to read it"

"Telescopes are confusing. I understand most of the components, but for some reason the eye piece always gets me."

"Retrograde Motion, I am confused by the start and end point."

"The essays are the most confusing subject I am studying for on this midterm."

"Probably the moon phases would be the most confusing to me, at least before you explained them. And why do you keep using incorrect grammar for your questions in the reading assignments. 'Your most interesting/confusing subject' Should it instead be "'The most confusing subject, to you'?"

"The earth-moon diagram related questions are most confusing for me. Even when i draw the diagram im still sometimes confused."

"Lunar Phases; The lunar phases should be somewhat easy but it isn't do to it's seemingly changing phases on different days."

"For some reason I just don't get the Sun stuff. I don't know why."

"the signs used in astrology are confused cuz they dont actually match up and make me angry."

"i thing the most confusing was the starwheel because i feel like i didnt get enough information on how to use it."

"I think photons because I was a little late and you had already started on notes."

"the layers of the sun, because the i confuse the names of them"

"The times of the day and the moon cycles. It was just difficult to remember the correct order."

"he whole semester has been a little confusing, it's just tough to grasp some scientific concepts."

"I thought locating the planets was especially confusing, and I'm still not sure on the subject. Also, the umbra/penumbra stuff was confusing, but I'm glad we went over it in class."

"Retrograde motion. I get confused how it appears to go backwards.."

"I dont know"

"Retrograde motions"

"I had trouble grasping the concept of retrograde motion and how planets appear to move backwards"

"Telescopes, that sas is always confusing me because im not interested in telescopes."

"I think remembering whether to multiply the length of the telescope by one or by two was confusing. Again, that will be my focus point while studying tomorrow."

"The snowboarder. Death to the snowboarder."

"The different layers of the suns atmosphere are confusing because of their similar names"

"most of it has been confusing for me, but I am catching up on some."

"TELESCOPES"

"telescopes i don't feel like we went over them a lot in class and there is a lot of memorizing involved in understanding them."

"uhhhh... all of them because they all sound like the same thing... and because I am not an astronomer."

"Why sun spots last for so long when they are around so much other heat why can't they heat up?.."

"in class assignment #6 b/c i wasn't in class so i had no idea what was going on. very frustrating."

"What I just said in that box ^^"

"eclipses- i still have trouble knowing when the moon is an eclipse and then having to identify which one it is."

"every single thing. this class is confusing and the book makes it even more confusing."

"Constellations, because the star chart is designed in a confusing manner"

"Idk"

"when the moon rises and sets and all that stuff"

"All of it"

"definitely the moon cycles because it is an abstract concept of the way the moon cycles rotate."

"AStronmers because I have a tough time remembering"

"the different theories of planet movements."

"The problems that have to do with the diagram of earth, the sun, and other planets and deciding which planet is in view of an observer on earth at a certain time! I was absent for this class plus I am directionaly(probably not a word) challenged."

"The position of the moon becase everything is always backwards."

"I do not thing I will understand the telescopes portion of the exam because I do not understand why telescopes are better than others,and why some are better than others. It's also because I would just rather use a telescope that someone else already decided is good."

"Telescope just confuses me."

"I think the most difficult for me is trying to keep all the different astronomers and their theories and laws straight."

"how telescopes work."

Online reading assignment question: interesting Midterm 1 astronomy topics

Astronomy 210 Reading Assignment 7, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

110316-interestingwordle
http://www.flickr.com/photos/waiferx/5532854215/
Originally uploaded by Waifer X

Wordle.net tag cloud for interesting topics covered in Midterm 1, generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA (http://www.wordle.net/show/wrdl/3315149/Untitled).

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

List at least three words describing interesting subjects covered in class (up through this midterm). (Graded for completion.)

[Responses have been edited to consolidate related common subjects.]

Student responses
Sections 30674, 30676

telescopes, moonphases moonrise, moonset, planetfinding
moonphases electromagneticradiation
stars, Sun, telescopes
eclipses
stars Moon telescope
eclipses, sunalogies identification
interesting, notconfusing easy
Moon Sun
planets, stars, moonphases
telescopes, moonphases, starwheel
moonphases
moonphases, eclipses, telescopes
Sun, quantummechanics, telescopes
Keplerslaws
starwheel
starwheel horoscopes stars
astronomers moonphases spectra
moonphases starpositions stellarstructure
planets, moonphases, starwheel
moonphases, electromagneticradiation, Sun
moonphases and moonset moonrise
hot, farout, bright
thoughtproducing, amazing, descriptive
fascinating, fun exciting
Moon, Earth planets, stars
quantummechanics, corona :)
moonphases, enjoyable applicable
moonphases, motions cycles, stars
orbit astronomers telescopes
moonphases, spectra, eclipses
telescopes, moonrise, moonset
moonphases, planets, umbra
eclipses, electromagneticradiation, chromosphere
Idontknow
Moon, electromagneticradiation, telescopes
Confusing, contradictory, wonderful
moonphases, eclipses, planets
telescopes, moonphases, Astronomers
misosoup, Tychosnose, drinkinglavalamps
terminator
new interesting difficult
moonphases, zodiac, stars
astronomers zodiac constellations sunrise sunset seasons
everything
sunspots Keplerslaws planetarymotion
moonphases eclipses
Sun, Moon, Earth
moonphases, sunalogies, Bowenobservatoryvisit
astronomers, galaxy, distance
easy, straightforward, understandable
Moon stars Mars
Sun, stars gravity
Sun eclipses stars
photosphere, chromosphere, corona
stars apparentmagnitude absolutemagnitude
telescopes, moonphases, eclipses
moonphases history astronomers electromagneticradiation
eclipses waning gibbous starwheel
moonphases, astrology Sun
spectra Moon Sun
new, different, exciting
electromagneticradiation Sun

Describe your most interesting subject, and briefly explain why this subject interested you. (Graded for completion.)

The following are all of the student responses to this question, verbatim and unedited.

It was interesting to learn about the moon phases because it was something new."

"The most interesting subject that was covered in the midterm was the moon phases, because it is so cool on how to the the times of the moon and the phases they are in."

"I like the stuff with the starwheel and the way the stars move."

"I enjoyed learning about the eclipses because I was able to China and see a total eclipse (even though it was clouded out I still have 5 minutes shadow time) and I hope to go to Australia in 2012 to witness another one."

"how we can measure how far away stars are because i just dont understand how that is possible"

"the spectrum of light graph because its economically interesting."

"The most interesting subject for me was the moon phases. i seem to be able to do those fairly easily."

"being able to use the star wheel. i thinks its interesting because its cool to look up at the sky during night and see all the stars, and now that i can look them up on the star wheel makes it even better."

"stars because its interesting how they all look different."

"I liked learning about telescope powers because I can see this being applicable to a real life situation: buying a telescope either for myself or as a gift."

"The different moon phases. I didn't realize before how the changed phases and the different phases being highest overhead at different times of month."

"Eclipses were very interesting."

"The different types and properties of electromagnetic radiation. I found how different wavelengths had different properties interesting."

"the car horn changing pitch, didnt expect that waves could work in that sense.."

"Finding out that the zodiac sighs are wrong when you look on wikipedia"

"My favorite topic we have covered so far is moon phases. Although they may be confusing, I like that I can apply the information"

"I have learned from this class to my everyday life. Whenever I see the moon outside I try to identify what phase it is in."

"Spectrums were what I found interesting since it's like fitting a puzzle together, you need all the pieces down to find out you're missing one."

"Moon phases are most interesting to me because I like being able to determine the next phase of the moon"

"Moon Phases. I find it really easy to determine what phase the moon is when it's rising, setting or at its highest point."

"The Sun, I was able to comprehend the differently layers and how to identify them."

"It's easy if you just remember the times and where all the phases are."

"HOT!!! self explanatory."

"The moon phases are interesting because i never really knew all of them."

"The Sun ; There was more information about the Sun that I did not know about as well adding on to what I already know."

"I liked learning about the Moon because I have always wondered about the different phases."

"Eclipses, they're pretty sick."

"i liked learning about how and why the seasons change. it's cool to know this information so you can sound like an arrogant know it all when discussing the weather with your friends."

"I'd have to say that would be stuff about stars because I'm learning a lot of stuff I never knew."

"i liked the theories of orbit and the cannonball because although it was hundreds of years ago, the relativity still makes sense"

"The types of wavelengths that can be gathered by certain levels in elevation. It's an interesting concept to think that electromagnetic radiation is both a wave and particle."

"The most interesting subject for me was the moon rise and set times. It's pretty interesting that they know exactly when the moon will rise and set even years from now."

"I thought the section on eclipses was really interesting, even though I still don't fully understand it, but I'm about to study so hopefully I will by Wednesday!"

"The sun"

"I dont know"

"Light and how the different types of light/ color affect the hotness or coldness of the stars"

"I liked learning about the different astronomers and their past's because I enjoy history."

"I like the moon phasing and setting because I understand that."

"I have enjoyed figuring out what phase the moon is in at different times of the day. I also like learning about how people discover new ideas- like figuring out that the sun, not the earth, is the center of our solar system."

"Starwheels are fun, and if I am ever lost I can now find my way to the North Pole, unless it is daytime and hadn't smoked something."

"retrograde motion because of its unusual occurance"

"phases of the moon because I have never known but have always wanted to before this class."

"Moon phases, I like it because I can use it in every day life. I love looking up in the skye and knowing what phase it is in."

"Moon phases"

"I think the different models by astronomers is the most interesting because it is interesting to see the different theories and how they are similar or different"

"There is too many to pick ."

"sound waves. it was interesting to learn about where you need to be to hear certain sound waves."

"The sun's various layers. Taking an object one see's on a daily basis and breaking it down to its actual elements was pretty cool."

"i have enjoyed learning about the different phases of the moon and what phase it's in when it is highest overhead."

"I think that eclipses are very interesting. I never knew you could actually see them."

"Planets arrangements, i always thought planets were interesting and always wanted to look at them through a telescope"

"Idk"

"mars and the elipses that the planets travel in"

"i dont know"

"Kirchoff's Laws; it was easy for me to grasp and I also find it very interesting to think that it is happening in the sun and everyday life"

"Absolute and apparent magnitude, I like it because I can apply it to what I see in the sky."

"the different types of eclipses and how rare some types are."

"I enjoyed the section on the historical Astronomers (chp. 3) because I really enjoy history of any nature."

"The chapter on the scientists and laws was interesting considering they discovered things without technology."

"So far the most interesting thing I have learned about has been the starwheel because I like stars"

"Most interesting subject I'm interested in is eclipses because of it's unique picture and of it's rarity."

"I don't know that I can pick just one; everything has been pretty interesting so far."

"the twinkling effect"

20110319

Astronomy in-class activity: OBAFGKM poetry slam (SLO)

stronomy 210, Spring Semester 2011
Cuesta College, San Luis Obispo, CA
(San Luis Obispo Campus)

Astronomy 210 In-class activity 14: OBAFGKM Poetry Slam

Students were instructed to use at least OBAFGKM, and/or part or all of the additional OBAFGKMRNSC or OBAFGKMLT extensions to individually write an original, coherent and an appropriate (nothing worse than "PG-13" rated!) mnemonic, and to give a rousing reading of their OBAFGKM mnemonic poem for the class.

Only Boys At Fairs Get Kicked Making Lame Taunts
--D. A.

Oh Boy, A Fat Girl Kicked My Left Testicle
--M. B.

Onion-Breather Astronomers Frighten Good, Kind Mr. Len
--D. B.

Only Badass Astronomers Freakin Go Kayaking Man
--M. C.

Oh Baby A Ford Galaxy Killed Me
--R. D.

Orange Bears Always Fight Gay Klan Members
--M. D.

Only Belle Abhors Feisty Gaston's Kind Marriage Requests
--J. H.-D

Only Ballin' Aliens Fly Gnarly Keyless Machines
--J. D.

Overcoming Basic Astronomy Final Gonna Kill Me
--J. G.

Ostrich Babies Assemble For Gambling Kangaroo Muds
--P. G.

Only Bieber Allows Frantic Girls' Kisses on Mondays
--N. H.

Oh Boy Another Friday night Gave Killer Munchies
--S. H.

Off Brand Aftermarket Footwear Gets Kinda Messed Up Some Times
--D. A. J.

Optative Birthdays Are Full (of) Gallivanting. Keep (the) Memories. Love (the) Times.
--H. J.

Oh Behave About Frolicking Gorillas Kicking Marky Mark
--C. J.

Oh Be A Friend, Give Kisses More!
--L. L.

Otters Bask Among Fresh Gardens of Kelp Masses
--H. M.

Oh Boy All Family Get-togethers Kill Me
--D. M.

Our Brother Attacked Flying Growing Killer Monkeys
--J. M.

Only Brilliant Astronomers Find Great Killer Meteors
--An. M.

Ostrich Balls Are From Gross Korean Meals (we ate) Last Time
--Au. M.

Only Bill Always Felt Guilty Kissing Monkeys
--D. M.

Outraged Bear Attacks Family of Gangsta Koala Murdering
--Z. N.

Once By A Famous Giant Kasino My Rude Nephew Shouted Curse words
--E. O.

Only Baseball And Football Get Killer Money
--E. P.

Over-eating Brothers Always Finish Good Korean Meals
--K. P.

Orbiting Ballistic Aircraft Furiously Giving Kinetic Motion!
--E. R.

Orion's Belt Always Fits Good with Kepler's Model
--J. R.

Oh Baby Almost Freakin Gonna Kry Myself to sleep
--T. R.

Obviously Bears Always Forget Good Kind Manners
--B. S.

Only Brats Are Foolish Girls Killing Men
--S. S.

On Boring Afternoons Fun Games My Life Thrilling
--E. S.

Only Baseballs A Favorites Get Killer Money
--G. S.

Obama Bought A Freakin Giant to Kill Men Like the Taliban
--M. T.

Old Birds Are Forever Going Koo-koo in My Little Tree
--S. T.

Obama Bakes Apple pie For Ghetto Kids' Moms
--A. U.

Obama Bashes Americans For Getting Korean Mangoes
--A. V.

Oranges Beats Apples From Giving Killer Mangos
--S. V.

Our Brother Admits Forgetting Good Karma Man!!!
--S. W.

Previous post:

Astronomy in-class activity: OBAFGKM poetry slam instructions.

Astronomy in-class activity: OBAFGKM poetry slam (NCC)

Astronomy 210, Spring Semester 2011
Cuesta College, San Luis Obispo, CA
(North County Campus)

Astronomy 210 In-class activity 14: OBAFGKM Poetry Slam

Students were instructed to use at least OBAFGKM, and/or part or all of the additional OBAFGKMRNSC or OBAFGKMLT extensions to individually write an original, coherent and an appropriate (nothing worse than "PG-13" rated!) mnemonic, and to give a rousing reading of their OBAFGKM mnemonic poem for the class.

Only Brilliant Astronomers Freaken Give Kim Millions
--Y. A.

Our Butts And Feet Got Kinks Man
--C. A.

Our Beautiful Apples Fell, Grossly Killing Martha
--As. B.

Oatmeal Breakfasts Are Fine, Grumpy Kids Make Random Noises to Stop Chewing
--Am. B.

Objects Be Apparent From Galaxies, Knew M______
--M. B.

Octopus Babies Are From Gnome Killing Mobs
--J. B.

Oswald Bounds Away from Grumpy Koala Mafia
--B. B.

Our Brave Army Fight Germs Killing Military Rebels Never Sound Cultures Love Them
--E. B.

On Back And Front Gaining Knowledge Makes Real Nice Sense Concentrate
--T. B.

Obviously Bats Are Filling Good at Keeping Monkeys
--M. C.

Old Bears, Away From Good Kind Moose, Run Near Secluded Clearings
--C. D.

Only Bowser Attacks Famous Great King Mario
--C. E.

Oh Baby A Freak Gonna Kill Me
--D. F.

Obama, Barack Always Farts (while) Giving Kisses (to) Michelle
--K. F.

Old Babies Ask For Gerber, Kraft Mac & Cheese
--X. G.

Only Bad Ass Felines Growl (at) Kitchen Machines
--E. H.

Observe Bombing Air-raids For Giant Killing Machines
--K. H.

Old Baboons Are Fairly Good Kool-Aid Makers Respectfully, Not Smelly Chimpanzees
--L. H.

Only Brilliant And Focused Guys Kiss Moms
--B. H.

Obama Bet Adam Five Grenade Kaboom Muffins
--T. H.

Only Bad Ass Friends Give Kailey Money
--K. L.

Old Bachelors And Friends Go Kipping Mondays
--A. L.

Once Befriended A F*****, Guy Knew my Mother
--T. L.

Obnoxious Betelgeuse Acquires Foreign Gangster's Kite Money
--J. L.

Only Batman And Flash Go Kick Manray
--D. N.

Only Babies Are Fed Grape Kittle Munchies
--R. O.

Oh Blue Astronomically Far Giant Kepler Moon
--D. P.

Oh Baby Aren't Flowers Gorgeous, Kevin Marry me!
--E. S.

Omar Bradley's Aunt, and Father Got Kind of Mad
--D. S.

Oh Be A Fine Guy Kiss Me!
--S. S.

Orbital Ballistic Autonomously Flight Guided Kinetic Missile
--B. T.

Only Butterflies Attack Flying Gorillas Killing Many
--H. T.

Oh, Bieber's A Faker, Gonna Kill Music
--M. T.

Orangutan Babies Are Funny Game Knowing Monkeys
--E. V.

Oprah Better Apologize For Googling the Kardashians' Men
--A. V.

Outta Beer And Feeling Great, Kiss Me!
--K. W.

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Astronomy in-class activity: OBAFGKM poetry slam instructions.

20110318

Astronomy current events question: Mars carbon dioxide presence

Astronomy.com editors, "Some of Mars' Missing Carbon Dioxide May Be Buried," March 9, 2011
http://astronomy.com/en/News-Observing/News/2011/03/Some%20of%20Mars%20missing%20carbon%20dioxide%20may%20be%20buried.aspx

__________ observed by NASA's Mars Reconnaissance Orbiter may be evidence of where Mars' ancient atmosphere disappeared to.
(A) Shifting positions of boulders and other rock debris.
(B) Wearing down of angular rock formations.
(C) Light reflected by rocks exposed by meteor impacts.
(D) The appearance, growth, and fading of dark rivulets.
(E) Accumulation of ice in shadowed north and south pole craters.

Correct answer: (C)

Student responses
Sections 30678, 30679, 30680
(A) : 10 students
(B) : 12 students
(C) : 14 students
(D) : 8 students
(E) : 6 students

Astronomy current events question: water flowing on Mars?

Kelly Beatty, "Is Water Flowing on Mars?," March 11, 2011
http://www.skyandtelescope.com/news/home/117806243.html

__________ observed by NASA's Mars Global Surveyor may be evidence of water flowing on Mars.
(A) Shifting positions of boulders and other rock debris.
(B) Wearing down of angular rock formations.
(C) Light reflected by rocks exposed by meteor impacts.
(D) The appearance, growth, and fading of dark rivulets.
(E) Accumulation of ice in shadowed north and south pole craters.

Correct answer: (D)

Student responses
Sections 30678, 30679, 30680
(A) : 3 students
(B) : 9 students
(C) : 1 student
(D) : 20 students
(E) : 16 students

Astronomy current events question: Sendai earthquake "supermoon?"

Phil Plait, "No, the 'Supermoon' Didn’t Cause the Japanese Earthquake," March 11, 2011
http://blogs.discovermagazine.com/badastronomy/2011/03/11/no-the-supermoon-didnt-cause-the-japanese-earthquake/

The Sendai earthquake and tsunami in Japan was most definitely not caused by the moon because:
(A) there is no correlation between earthquakes and moon phase/position.
(B) the moon's gravity is always less than the sun's gravity.
(C) there is no evidence of moonquakes detected by lunar landers.
(D) the distance to the moon is actually gradually increasing each year.
(E) the moon's magnetic field is much stronger than its gravitational field.

Correct answer: (A)

Student responses
Sections 30678, 30679, 30680
(A) : 40 students
(B) : 1 student
(C) : 2 students
(D) : 3 students
(E) : 3 students

Astronomy current events question: Voyager 1 at heliosheath

Jia-Rui Cook, "Voyager Seeks the Answer Blowin' in the Wind," March 8, 2011
http://www.nasa.gov/mission_pages/voyager/voyager20110308.html

To prepare to gather data on the outer solar system's heliosheath, NASA's Voyager 1 spacecraft:
(A) used retrorockets to slow down to a complete stop.
(B) upgraded and rebooted its operating system.
(C) temporarily disconnected its nuclear power source.
(D) tested its gyroscopes to turn itself around.
(E) sped up to 1% of the speed of light.

Correct answer: (D)

Student responses
Sections 30678, 30679, 30680
(A) : 8 students
(B) : 6 students
(C) : 2 students
(D) : 31 students
(E) : 3 students

Cuesta College North County campus star party

110310-1220606
http://www.flickr.com/photos/waiferx/5527513646/
Originally uploaded by Waifer X

Waxing crescent moon, March 10, 2011, photographed with a Panasonic Lumix LZ-8 camera through a Orion 10" reflector at Cuesta College North County campus, Paso Robles, CA. Photo by Cuesta College Physical Sciences Division instructor Dr. Patrick M. Len.

110310-1220611
http://www.flickr.com/photos/waiferx/5527514072/
Originally uploaded by Waifer X

Cuesta College Astronomy 210L students and guest (and a cold dog) at a North County campus star party.

Sights seen:
M42 (Orion nebula)
Castor, Pollux
Sirius
Waxing crescent moon

20110317

Physics quiz archive: interference, electrostatics

Physics 205B Quiz 3, spring semester 2011
Cuesta College, San Luis Obispo, CA

Section 30882, version 1

Section 30882 results
Exam code: quiz03F3ld

 0- 6 : 
 7-12 : 
13-18 : ****  [low = 18]
19-24 : ***  [mean = 19.7 +/- 2.4]  [high = 24]
25-30 :

20110316

Physics quiz question: out of phase radio tower interference

Physics 205B Quiz 3, spring semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 25.3.

Two coherent radio transmitters broadcast out of phase signals with the same wavelength. A radio antenna receives a constructive interference signal from these transmitters, and is located 1.85 km away from one transmitter, and 2.25 km away from the other transmitter. The longest possible wavelength of the transmitters is:
(A) 0.20 km.
(B) 0.27 km.
(C) 0.40 km.
(D) 0.80 km.

Correct answer: (D)

The path-length difference ∆l = (2.25 km - 1.85 km) = 0.40 km. Since the two sources are out-of-phase, then the constructive interference condition becomes:

∆l = (m + 1/2)·λ,

where the longest possible wavelength is given by:

∆l/(m + 1/2) = λ = 0.80 km, by choosing m = 0.

Response (A) is ∆l/2; response (B) is (2/3)·∆l, which is the second-longest possible wavelength; response (C) is delta(l).

Student responses
Section 30822
Exam code: quiz03F3ld
(A) : 1 student
(B) : 2 students
(C) : 4 students
(D) : 0 students

Success level: 0%
Discrimination index (Aubrecht & Aubrecht, 1983): 0

In the subsequent lecture, students were instructed to re-do this problem in small groups on whiteboards, solving for the longest possible wavelength (0.80 km), but also to find the second-longest possible wavelength as well (0.27 km).

110314-1220612
http://www.flickr.com/photos/waiferx/5526922797/
Originally uploaded by Waifer X

20110315

Physics quiz question: laser diffraction through a single slit

Physics 205B Quiz 3, spring semester 2011
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 25.49

Light from a green laser of wavelength 550 nm passes through a single slit to form a diffraction pattern on a screen 4.0 m from the slit, where the width of the central maximum on the screen is 14 mm. The width of the slit is:
(A) 2×10^–8 m.
(B) 6×10^–8 m.
(C) 8×10^–5 m.
(D) 3×10^–4 m.

Correct answer (highlight to unhide): (D)

From trigonometry, the relation between the angle θ and the adjacent leg L = 4.0 m (distance from the single slit to the screen") and the opposite leg y = 7 mm (one-half of the "width of the central maximum on the screen):

tanθ = y/L,

θ = tan^–1(y/L).

Then from the first minima equation (which uses the angle that measures one-half of the "width of the central maximum on the screen"), where W is the width of the slit:

W·sinθ = (1)·λ,

W = λ/sinθ,

W = λ/(sin(tan^–1(y/L)),

W = (550×10^–9 m)/sin(tan^–1((7×10^–3 m)/(4.0 m))) = 3.14286195535×10^–4 m,

which to one significant figure means the slit is 3×10^–4 m wide.

(Response (A) is L·λ·y; response (B) is 4L·λ·y; response (C) is L·λ/(4y).)

Student responses
Section 30822
Exam code: quiz03F3ld
(A) : 2 students
(B) : 1 student
(C) : 2 students
(D) : 2 students

Success level: 29%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50

20110314

Astronomy quiz question: largest star

Astronomy 210 Quiz 4, spring semester 2011
Cuesta College, San Luis Obispo, CA

Which star is largest?
(A) B5 supergiant.
(B) K2 supergiant.
(C) M2 giant.
(D) O5 main sequence star.

Correct answer (highlight to unhide): (C)

Reading off of an H-R diagram (provided on this quiz), the B5 supergiant has a radius a bit less than 100 R_Sun, the K2 supergiant has a radius between 100-1,000 R_Sun, the M2 giant has a radius a little under 100 R_Sun, while O5 main sequence star is approximately 10 R_Sun in radius.

Section 30674
(A) : 7 students
(B) : 3 students
(C) : 20 students
(D) : 8 students

"Success level": 57% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.81
Exam code: quiz04nK4n

Astronomy midterm question: waning crescent scenario

Astronomy 210 Midterm 1, spring semester 2011
Cuesta College, San Luis Obispo, CA

Shown at right is a scene from an animated TV show. Discuss a specific plausible time (or range of times) for this scene, assuming that it is not an eclipse, using a diagram showing the positions of the sun, moon, Earth, and an observer on Earth.

(Image credit: Matt Groening, Futurama, "Rebirth," Season 6, Episode 1, 20th Century Fox Television, 2010,  http://www.gotfuturama.com/Multimedia/FrameGrabs/6ACV01/.)

Solution and grading rubric:

p = 20/20:
Correct. Phase as shown is waning crescent, which is highest overhead at 9 AM (rises at 3 AM, and sets at 3 PM, so any time within that range would be plausible, may restrict times to between 3 AM to 6 PM as the sky is still dark, and moon is not yet fully upright/on the meridian). Correct diagram and reasoning.
r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. Problems with either diagram, phase, or time.
v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Problems with diagram, phase, and time.
x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. Explanation based on eclipses, solstices, etc.
y = 2/20:
Irrelevant discussion/effectively blank.
z = 0/20:
Blank.

Grading distribution:
Section 30676
Exam code: midterm01sl7k
p: 22 students
r: 4 students
t: 8 students
v: 13 students
x: 2 students
y: 0 students
z: 0 students

A sample "p" response (from student 4351):

20110313

Astronomy midterm question: late-night Venus, Jupiter?

Astronomy 210 Midterm 1, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

[20 points.] An astronomy question on an online discussion board was asked and answered:

mickafeld: ...How do you [tell] the difference between Venus and Jupiter?
duke_of_uris: If you see a very bright planet late at night, it's Jupiter [and not Venus]...
-- http://au.answers.yahoo.com/question/index?qid=20100507202644AANiYYU

Discuss if this answer is correct or incorrect, and how you know this. Support your answer using a diagram showing the positions of the sun, Venus, Jupiter, Earth, and an observer on Earth.

Solution and grading rubric:

p = 20/20:
Correct. Correct and complete diagram, with Venus (inner heliocentric orbit) and Jupiter (outer heliocentric orbit); Jupiter can be seen late at night if it is near opposition to Earth, but Venus cannot in any part of its orbit.
r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. Typically has diagram of heliocentric orbits of Venus, Earth, and Jupiter, but discussion is problematic.
v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Diagram is problematic (Venus and Jupiter both in inner heliocentric orbits, or both in outer heliocentric orbits), but at least discussion is consistent with incorrect diagram.
x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. Problematic diagram (geocentric orbits, no orbits etc.), problematic discussion.
y = 2/20:
Irrelevant discussion/effectively blank.
z = 0/20:
Blank.

Grading distribution:
Section 30676
Exam code: midterm01sl7k
p: 18 students
r: 7 students
t: 5 students
v: 6 students
x: 12 students
y: 1 student
z: 0 students

A sample "p" response (from student 1103):