20110729

Education research: ALLS pre- to post-instruction attitude shifts (Cuesta College, spring semester 2011)

Student attitudes are assessed using an Astronomy Laboratory Learning Survey (ALLS), a five-point Likert scale questionnaire with demographic questions, and entry/exit evaluation questions (Patrick M. Len, in development) to Astronomy 210L students at Cuesta College, San Luis Obispo, CA. This laboratory course is a one-semester, adjunct course to Astronomy 210 lecture, and is taken primarily by students to satisfy their general education science laboratory transfer requirement.

The ALLS is administered as a pre-test on the first laboratory meeting, before any introduction/instruction took place; and as a post-test on the last laboratory meeting.

The results from the pre- and post-test questions follow below. Values for the mean and standard deviations are given next to the modal response category for each question, along with a Student t-test for the probability of null hypothesis rejection, and the class-wise Hake gain. (Matched-pair Hake gains were not calculated for each student, as pre-instruction values such as "5" would result in undefined values.) For statistical purposes, blank entries were treated as "3. Neutral," and multiply-circled entries such as "12," "23," "34," and "45" were treated as "1," "2," "4," and "5" respectively.
Cuesta College
Astronomy Laboratory Learning Survey (ALLS)
Pre- and Post-instruction results
Astronomy 210L spring semester 2011 sections 30678, 30679, 30680, 30682
(N = 67, matched-pairs only)

1. I am interested in using a telescope or binoculars for astronomy.
Pre-instruction
1. Strongly disagree 4 : ****
2. Disagree 11 : ***********
3. Neutral 26 : ************************** [3.2 +/- 1.1]
4. Agree 15 : ***************
5. Strongly agree 9 : *********

Post-instruction
1. Strongly disagree 0 :
2. Disagree 1 : *
3. Neutral 17 : *****************
4. Agree 29 : ***************************** [4.0 +/- 0.8]
5. Strongly agree 18 : ******************

Student t-test p = 0.0001 (t = -4.65, sd = 0.944, dof = 128)
Class-wise <g> = +0.43

2. Astronomy has little relation to what I experience in the real world.
Pre-instruction
1. Strongly disagree 11 : ***********
2. Disagree 27 : *************************** [2.3 +/- 0.8]
3. Neutral 23 : ***********************
4. Agree 4 : ****
5. Strongly agree 0 :

Post-instruction
1. Strongly disagree 16 : ****************
2. Disagree 30 : ****************************** [2.2 +/- 0.9]
3. Neutral 11 : ***********
4. Agree 8 : ********
5. Strongly agree 0 :

Student t-test p = 0.38 (t = 0.889, sd = 0.888, dof = 128)
Class-wise <g> = -0.05

3. I know where and how to look up astronomy information.
Pre-instruction
1. Strongly disagree 8 : ********
2. Disagree 15 : ***************
3. Neutral 20 : ******************** [2.9 +/- 1.1]
4. Agree 17 : *****************
5. Strongly agree 5 : *****

Post-instruction
1. Strongly disagree 0 :
2. Disagree 1 : *
3. Neutral 6 : ******
4. Agree 31 : ******************************* [4.3 +/- 0.7]
5. Strongly agree 27 : ***************************

Student t-test p < 0.0001 (t = -8.14, sd = 0.949, dof = 128)
Class-wise <g> = +0.66

4. I know where and how to find objects in the night sky.
Pre-instruction
1. Strongly disagree 6 : ******
2. Disagree 19 : *******************
3. Neutral 26 : ************************** [2.8 +/- 1.0]
4. Agree 12 : ************
5. Strongly agree 2 : **

Post-instruction
1. Strongly disagree 0 :
2. Disagree 1 : *
3. Neutral 13 : *************
4. Agree 39 : *************************************** [4.0 +/- 0.7]
5. Strongly agree 12 : ************

Student t-test p < 0.0001 (t = -8.13, sd = 0.831, dof = 128)
Class-wise <g> = +0.53

5. I am interested in news that is related to astronomy.
Pre-instruction
1. Strongly disagree 0 :
2. Disagree 5 : *****
3. Neutral 17 : *****************
4. Agree 26 : ************************** [3.8 +/- 0.9]
5. Strongly agree 17 : *****************

Post-instruction
1. Strongly disagree 0 :
2. Disagree 5 : *****
3. Neutral 13 : *************
4. Agree 32 : ******************************** [3.9 +/- 0.9]
5. Strongly agree 15 : ***************

Student t-test p = 0.84 (t = 0.199, sd = 0.882, dof = 128)
Class-wise <g> = +0.03

6. I often ask myself questions related to astronomy.
Pre-instruction
1. Strongly disagree 0 :
2. Disagree 14 : **************
3. Neutral 22 : ********************** [3.4 +/- 1.0]
4. Agree 20 : ********************
5. Strongly agree 9 : *********

Post-instruction
1. Strongly disagree 1 : *
2. Disagree 11 : ***********
3. Neutral 19 : *******************
4. Agree 23 : *********************** [3.5 +/- 1.0]
5. Strongly agree 11 : ***********

Student t-test p = 0.48 (t = -0.703, sd = 0.998, dof = 128)
Class-wise <g> = +0.08

7. I am comfortable using a calculator to make complex calculations.
Pre-instruction
1. Strongly disagree 5 : *****
2. Disagree 13 : *************
3. Neutral 17 : *****************
4. Agree 22 : ********************** [3.2 +/- 1.1]
5. Strongly agree 8 : ********

Post-instruction
1. Strongly disagree 5 : *****
2. Disagree 11 : ***********
3. Neutral 14 : **************
4. Agree 24 : ************************ [3.4 +/- 1.2]
5. Strongly agree 11 : ***********

Student t-test p = 0.45 (t = -0.755, sd = 1.16, dof = 128)
Class-wise <g> = +0.09

8. I can make sense of equations and scientific notation numbers.
Pre-instruction
1. Strongly disagree 5 : *****
2. Disagree 11 : ***********
3. Neutral 14 : **************
4. Agree 27 : *************************** [3.3 +/- 1.1]
5. Strongly agree 8 : ********

Post-instruction
1. Strongly disagree 5 : *****
2. Disagree 6 : ******
3. Neutral 16 : ****************
4. Agree 27 : *************************** [3.5 +/- 1.1]
5. Strongly agree 11 : ***********

Student t-test p = 0.39 (t = -0.855, sd = 1.13, dof = 128)
Class-wise <g> = +0.10

9. I prefer to work independently rather than in groups.
Pre-instruction
1. Strongly disagree 7 : *******
2. Disagree 14 : **************
3. Neutral 29 : ***************************** [2.9 +/- 1.0]
4. Agree 11 : ***********
5. Strongly agree 4 : ****

Post-instruction
1. Strongly disagree 12 : ************
2. Disagree 20 : ********************
3. Neutral 23 : *********************** [2.5 +/- 1.1]
4. Agree 6 : ******
5. Strongly agree 4 : ****

Student t-test p = 0.085 (t = 1.74, sd = 1.06, dof = 128)
Class-wise <g> = -0.15

10. I can understand difficult concepts better if I am able to explain them to
others.
Pre-instruction
1. Strongly disagree 1 : *
2. Disagree 10 : **********
3. Neutral 22 : **********************
4. Agree 24 : ************************ [3.4 +/- 1.0]
5. Strongly agree 8 : ********

Post-instruction
1. Strongly disagree 1 : *
2. Disagree 2 : **
3. Neutral 15 : ***************
4. Agree 29 : ***************************** [3.9 +/- 0.9]
5. Strongly agree 18 : ******************

Student t-test p = 0.0020 (t = -3.16, sd = 0.917, dof = 128)
Class-wise <g> = +0.32

11. I can understand difficult concepts better if I am able to ask lots of
questions.
Pre-instruction
1. Strongly disagree 0 :
2. Disagree 5 : *****
3. Neutral 15 : ***************
4. Agree 35 : *********************************** [3.8 +/- 0.8]
5. Strongly agree 10 : **********

Post-instruction
1. Strongly disagree 0 :
2. Disagree 3 : ***
3. Neutral 14 : **************
4. Agree 29 : ***************************** [4.0 +/- 0.8]
5. Strongly agree 19 : *******************

Student t-test p = 0.14 (t = 0.822, sd = 0.822, dof = 128)
Class-wise <g> = +0.18

12. Knowledge in astronomy consists of many pieces of information each of
which applies primarily to a specific situation.
Pre-instruction
1. Strongly disagree 0 :
2. Disagree 5 : *****
3. Neutral 37 : ************************************* [3.3 +/- 0.7]
4. Agree 20 : ********************
5. Strongly agree 3 : ***

Post-instruction
1. Strongly disagree 0 :
2. Disagree 5 : *****
3. Neutral 24 : ************************
4. Agree 29 : ***************************** [3.6 +/- 0.8]
5. Strongly agree 7 : *******

Student t-test p = 0.046 (t = -2.02, sd = 0.740, dof = 128)
Class-wise <g>> = +0.16

13. I am good at math.
Pre-instruction
1. Strongly disagree 5 : *****
2. Disagree 16 : ****************
3. Neutral 28 : **************************** [2.9 +/- 1.0]
4. Agree 12 : ************
5. Strongly agree 4 : ****

Post-instruction
1. Strongly disagree 7 : *******
2. Disagree 16 : ****************
3. Neutral 19 : ******************* [3.0 +/- 1.2]
4. Agree 16 : ****************
5. Strongly agree 7 : *******

Student t-test p = 0.63 (t = -0.484, sd = 1.09, dof = 128)
Class-wise <g> = +0.04

14. I am good at science.
Pre-instruction
1. Strongly disagree 0 :
2. Disagree 10 : **********
3. Neutral 34 : ********************************** [3.2 +/- 0.7]
4. Agree 19 : *******************
5. Strongly agree 2 : **

Post-instruction
1. Strongly disagree 1 : *
2. Disagree 17 : *****************
3. Neutral 23 : *********************** [3.2 +/- 1.0]
4. Agree 18 : ******************
5. Strongly agree 6 : ******

Student t-test p = 0.203 (t = 0.203, sd = 0.864, dof = 128)
Class-wise <g> = -0.02

15. This course will be/was difficult for me.
Pre-instruction
1. Strongly disagree 2 : **
2. Disagree 14 : **************
3. Neutral 28 : **************************** [3.1 +/- 0.9]
4. Agree 18 : ******************
5. Strongly agree 3 : ***

Post-instruction
1. Strongly disagree 13 : *************
2. Disagree 25 : ************************* [2.4 +/- 1.0]
3. Neutral 18 : ******************
4. Agree 7 : *******
5. Strongly agree 2 : **

Student t-test p = 0.0001 (t = 4.19, sd = 0.964, dof = 128)
Class-wise <g> = -0.37

Note that this semester (spring semester 2011) was the first implementation of a backwards faded scaffolding curriculum (Slater, Slater, and Lyons, 2010), previous semesters (fall semester 2011 and earlier) used a conventional "cookbook" laboratory curriculum. The student learning outcomes for the conventional "cookbook" laboratory curriculum:
  • Keep abreast of present-day discoveries and developments in astronomy (current events).
  • Construct and use devices to measure locations and sizes on the celestial sphere (observational astronomy).
  • Apply laws of spectroscopy and gravitation to remotely determine properties of satellites, planets, and stars (astronometry).
  • Develop and test physical models of the properties of solar system bodies (planetology).
  • Collect data, evaluate the data using error analysis, draw conclusions from the data.
  • Explain the information in a laboratory report.
Compare to the student learning outcomes for the backwards faded scaffolding laboratory curriculum:
  • Keeping abreast of present-day discoveries and developments in astronomy (current events).
  • Developing scientific evidence-based research questions.
  • Developing procedures to gather evidence in order to answer research questions.
  • Making appropriate evidence-supported conclusions.
  • Explaining research findings in a report, poster, or presentation.
  • Evaluating evidence to determine whether or not it appropriately answers a research question.
The following results were all comparable between the BFS and conventional curriculum labs, suggesting that (this version of the) ALLS either (a) cannot distinguish how these two types of labs affected student attitudes differently, or (b) these two types of labs do not affect student attitudes differently. Future revisions to the ALLS may include questions more specifically designed to elicit student attitude changes that may (or may not) stem from the new backwards faded scaffolding laboratory curriculum.
A statistically significant (p < 0.05) positive shift was observed for the interest in using telescopes/binoculars in astronomy (question 1), which was comparable to the results from fall semester 2011. There was a statistically insignificant positive shift in spring semester 2010, and notably a statistically significant (p < 0.05) negative shift in fall semester 2009! Also no statistically significant (p > 0.05) shifts were observed for relating astronomy to personal experience (question 2), interest in astronomy-related news (question 5), pondering astronomy-related questions (question 6), self-efficacy in use of calculators and math in astronomy (questions 7 and 8), individual/group learning habits (questions 9 and 11), and self-efficacy in math/science (questions 13 and 14). However, there are statistically significant (p < 0.05) gains in being able to find astronomy-related news/information (question 3), finding night sky objects (question 4), understanding concepts better by explaining (question 10), disconnectedness in astronomy concepts (question 12), and rating the expected/experience difficulty of this course (question 15).

Previous posts:

20110728

Education research: ALLS post-instruction opinion results (Cuesta College, spring semester 2011)

Student attitudes are assessed using an Astronomy Laboratory Learning Survey (ALLS), a five-point Likert scale questionnaire with demographic questions, and entry/exit evaluation questions (Patrick M. Len, in development) to Astronomy 210L students at Cuesta College, San Luis Obispo, CA. This laboratory course is a one-semester, adjunct course to Astronomy 210 lecture, and is taken primarily by students to satisfy their general education science laboratory transfer requirement.

The ALLS is administered as a pre-test on the first laboratory meeting, before any introduction/instruction took place; and as a post-test on the last laboratory meeting.

The results from the post-test opinion questions follow below. Only matched-pair results are shown, for students who were also able to take the pre-instruction ALLS at the first laboratory meeting. Values for the mean and standard deviations are given next to the modal response category for each question.
Cuesta College
Astronomy Laboratory Learning Survey (ALLS)
Post-instruction opinion results
Astronomy 210L spring semester 2011 sections 30678, 30679, 30680, 30682
(N = 65, matched-pairs only)

16. Astronomy lab was (or would have been) helpful for learning in lecture.
1. Strongly disagree 0 :
2. Disagree 4 : ****
3. Neutral 14 : **************
4. Agree 28 : ***************************** [3.9 +/- 0.9]
5. Strongly agree 18 : ******************

17. I understand more about astronomy concepts because of what I learned in lab.
1. Strongly disagree 0 :
2. Disagree 1 : *
3. Neutral 7 : *******
4. Agree 34 : ********************************** [4.2 +/- 0.7]
5. Strongly agree 23 : ***********************

18. Astronomy lab was an enjoyable experience.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 3 : ***
4. Agree 25 : *************************
5. Strongly agree 37 : ************************************* [4.5 +/- 0.6]

19. Math used in astronomy lab was difficult.
1. Strongly disagree 19 : *******************
2. Disagree 32 : ********************************
3. Neutral 11 : *********** [2.0 +/- 0.9]
4. Agree 2 : **
5. Strongly agree 1 : *

20. It was hard to understand concepts in astronomy lab.
1. Strongly disagree 11 : ***********
2. Disagree 41 : ***************************************** [2.1 +/- 0.7]
3. Neutral 11 : ***********
4. Agree 1 : *
5. Strongly agree 1 : *

21. This course helped me see how astronomy is related to other sciences such as
geology, physics, and chemistry.
1. Strongly disagree 0 :
2. Disagree 7 : *******
3. Neutral 18 : ******************
4. Agree 25 : ************************* [3.7 +/- 0.9]
5. Strongly agree 15 : ***************

22. I asked a lot of questions in astronomy lab.
1. Strongly disagree 6 : ******
2. Disagree 17 : *****************
3. Neutral 22 : ********************** [2.9 +/- 1.1]
4. Agree 15 : ***************
5. Strongly agree 5 : *****

23. I generally understood what was needed to be done in astronomy lab.
1. Strongly disagree 0 :
2. Disagree 1 : *
3. Neutral 5 : *****
4. Agree 38 : ************************************** [4.2 +/- 0.6]
5. Strongly agree 21 : *********************

24. My work in astronomy lab was graded fairly.
1. Strongly disagree 1 : *
2. Disagree 0 :
3. Neutral 5 : *****
4. Agree 14 : **************
5. Strongly agree 45 : ********************************************* [4.6 +/- 0.8]

25. I did a lot of explaining to other students in astronomy lab.
1. Strongly disagree 0 :
2. Disagree 4 : ****
3. Neutral 29 : ***************************** [3.5 +/- 0.8]
4. Agree 25 : *************************
5. Strongly agree 7 : *******

26. I was generally confused about what was going on in astronomy lab.
1. Strongly disagree 17 : *****************
2. Disagree 37 : ************************************* [1.9 +/- 0.7]
3. Neutral 11 : ***********
4. Agree 0 :
5. Strongly agree 0 :

27. I would recommend astronomy lab to other students.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 2 : **
4. Agree 23 : ******************
5. Strongly agree 40 : **************************************** [4.6 +/- 0.6]

28. Astronomy lab should only be taken in the same semester as astronomy lecture.
1. Strongly disagree 4 : ****
2. Disagree 10 : **********
3. Neutral 23 : *********************** [3.3 +/- 1.1]
4. Agree 18 : ******************
5. Strongly agree 10 : **********

29. Astronomy lab should only be taken after completing the entire semester of
astronomy lecture.
1. Strongly disagree 9 : *********
2. Disagree 30 : ****************************** [2.3 +/- 0.9]
3. Neutral 22 : ************
4. Agree 4 : ****
5. Strongly agree 0 :

30. This course helped me feel more comfortable with the idea that many values in
science are uncertain to some degree.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 20 : ********************
4. Agree 30 : ****************************** [3.9 +/- 0.7]
5. Strongly agree 15 : ***************

Previous posts:

20110727

Education research: ALLS demographic results (Cuesta College, spring semester 2011)

Student attitudes are assessed using an Astronomy Laboratory Learning Survey (ALLS), a five-point Likert scale questionnaire with demographic questions, and entry/exit evaluation questions (Patrick M. Len, in development) to Astronomy 210L students at Cuesta College, San Luis Obispo, CA. This laboratory course is a one-semester, adjunct course to Astronomy 210 lecture, and is taken primarily by students to satisfy their general education science laboratory transfer requirement.

The ALLS is administered as a pre-test on the first laboratory meeting, before any introduction/instruction took place; and as a post-test on the last laboratory meeting.

The results from the pre-test demographic questions follow below. Only matched-pair results are shown, for students who were eventually able to take the post-instruction ALLS at the last laboratory meeting.
Cuesta College
Astronomy Laboratory Learning Survey (ALLS)
Demographic pre-instruction question results
Astronomy 210L spring semester 2011 sections 30678, 30679, 30680, 30682
(N = 65, matched-pairs only)

16. What is your gender?
(A) Female. [33]
(B) Male. [32]

17. Have you previously taken an astronomy lecture class?
(A) Yes. [19]
(B) No. [45]

18. Are you currently enrolled in an astronomy lecture class?
(A) Yes. [49]
(B) No. [15]

19. How many college science courses have you completed prior
to taking this course?
(A) None. [25]
(B) 1. [18]
(C) 2. [16]
(D) 3. [ 3]
(E) 4+. [ 3]

20. What is your college major (or current area(s) of interest
if undecided)? Choose as many areas of interest that apply.
(A) Business. [ 6]
(B) Education. [ 2]
(C) Humanities, Social Sciences, or the Arts. [23]
(D) Science, Engineering, or Architecture. [ 3]
(E) Other. [16]

21. Which of these college math classes have you completed
prior to taking this course? Choose as many classes that apply.
(A) Algebra. [46]
(B) Trigonometry. [ 6]
(C) Geometry. [17]
(D) Pre-calculus. [15]
(E) Calculus. [ 4]
(F) Statistics. [18]

Previous posts:

20110726

Education research: post-instruct. feedback on flashcards, reading assignments, homework reports (Cuesta College, Physics 205B, spring semester 2011)

Students taking Physics 205B (college physics, algebra-based, mandatory adjunct laboratory) at Cuesta College, San Luis Obispo, CA use flashcards to engage in peer-interaction ("think-(pair)-share") discussion questions during lecture, and complete weekly online reading assignments (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.

During the last week of instruction, students were given the opportunity to evaluate the instructional components of the course, and the use of flashcards, online reading assignments, and online homework reports (Matthew L. Trawick, The Physics Teacher, vol. 48, no. 2, p. 118) in an online "Learning Resource Survey" hosted by SurveyMonkey.com. Questions from section II are adapted from the Student Assessment of Learning Gains (SALG) survey (developed by Elaine Seymour, Wisconsin Center for Education Research, University of Wisconsin-Madison), and questions from section III (III.1, III.3, III.5, and III.7) were adapted from a "Clicker Attitude Survey" (N. W. Reay, Lei Bao, and Pengfei Li, Physics Education Research Group, Ohio State University).

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, III and V were randomly scrambled for each student.
Learning Resource Survey
Cuesta College
Physics 205B spring semester 2011 section 30882
(N = 7)

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


II. How much did each of the following aspects of the class help
your learning?

II.1 Lecture by instructor.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 3 : ***
5. Strongly agree 4 : **** [4.6 +/- 0.4]

II.2 Doing unassigned flashcard questions.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 2 : **
4. Agree 4 : **** [3.9 +/- 0.6]
5. Strongly agree 1 : *

II.3 Using flashcards to participate in class.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 2 : **
5. Strongly agree 5 : ***** [4.7 +/- 0.5]

II.4 Reading the textbook.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 1 : *
4. Agree 5 : ***** [4.0 +/- 0.5]
5. Strongly agree 1 : *

II.5 Demonstrations/videos in class.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 1 : *
4. Agree 1 : *
5. Strongly agree 5 : ***** [4.6 +/- 0.7]

II.6 Interacting with other students during class.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 3 : ***
5. Strongly agree 4 : **** [4.6 +/- 0.5]

II.7 Instructor follow-up on difficult online homework report problems.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 1 : *
4. Agree 2 : **
5. Strongly agree 4 : **** [4.4 +/- 0.7]

II.8 Online reading assignments.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 1 : *
4. Agree 4 : **** [4.1 +/- 0.6]
5. Strongly agree 2 : **

II.9 Online homework reports.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 3 : ***
4. Agree 4 : **** [3.6 +/- 0.5]
5. Strongly agree 0 :

II.10 Interacting with other students outside of class.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 2 : **
4. Agree 3 : *** [4.0 +/- 0.8]
5. Strongly agree 2 : **

II.11 Group problem solving sessions (on whiteboards).
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 3 : ***
5. Strongly agree 4 : **** [4.6 +/- 0.5]

II.12 Group concept mapping (on whiteboards).
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 3 : ***
5. Strongly agree 4 : **** [4.6 +/- 0.5]

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

III.1 I like using flashcards.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 4 : **** [4.4 +/- 0.5]
5. Strongly agree 3 : ***

III.2 Flashcards helped me understand lectures better.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 5 : ***** [4.3 +/- 0.5]
5. Strongly agree 2 : **

III.3 I would recommend using flashcards in future semesters of Physics 205B.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 3 : *** [4.5 +/- 0.5]
5. Strongly agree 3 : ***

III.4 I will avoid other classes using flashcards in future semesters.
1. Strongly disagree 2 : **
2. Disagree 5 : ***** [1.7 +/- 0.7]
3. Neutral 0 :
4. Agree 0 :
5. Strongly agree 0 :

III.5 Flashcards were a positive experience.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 1 : *
4. Agree 3 : *** [4.3 +/- 0.7]
5. Strongly agree 3 : ***

III.6 Too much time in class was spent using flashcards.
1. Strongly disagree 1 : *
2. Disagree 5 : ***** [2.0 +/- 0.5]
3. Neutral 1 : *
4. Agree 0 :
5. Strongly agree 0 :

III.7 Too many flashcard questions were asked.
1. Strongly disagree 1 : *
2. Disagree 5 : ***** [2.0 +/- 0.5]
3. Neutral 1 : *
4. Agree 0 :
5. Strongly agree 0 :

III.8 Using flashcards was difficult.
1. Strongly disagree 2 : **
2. Disagree 3 : *** [2.1 +/- 1.1]
3. Neutral 1 : *
4. Agree 0 :
5. Strongly agree 0 :

IV. (Optional.) Please type in any comments you may have regarding
the use of flashcards in Physics 205B.
"Although the students' understanding of the material is important, time management seems paramount when it comes to available class time."

"In general I felt that the flash cards helped me to better understand the concepts from lecture. Even though I don't always understand them, it really helps to go through them and discuss our answers and why we came to the conclusions we did. Helps to work on how to approach certain problems."

"I liked the fact that we could get our initial thoughts out with the flashcards during class and fix any misconceptions relatively quickly following the questions. I just wish there was an answer key to the questions online just in case we wanted to look over them again and just forgot to write the answers to some down in class."

"I felt flashcards were very helpful. Sometimes when I was confused on a subject, they helped clarify it. Flashcards also helped solidify if you really knew a subject or not. I like the interactive nature of flashcards. It makes you think instead of just copying notes down the entire class period."
V. Answer the following statements which may or may not describe 
your beliefs about working on the online reading assignments
in this class.

V.1 Online reading assignments were a positive experience.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 2 : **
4. Agree 5 : ***** [3.7 +/- 0.5]
5. Strongly agree 0 :

V.2 I like working on the online reading assignments.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 4 : **** [3.6 +/- 0.7]
4. Agree 2 : **
5. Strongly agree 1 : *

V.3 Too much time outside of class was spent working on online reading
assignments.
1. Strongly disagree 2 : **
2. Disagree 3 : *** [2.0 +/- 0.9]
3. Neutral 2 : **
4. Agree 0 :
5. Strongly agree 0 :

V.4 I will avoid other classes using online reading assignments in future
semesters.
1. Strongly disagree 2 : **
2. Disagree 5 : ***** [1.7 +/- 0.7]
3. Neutral 0 :
4. Agree 0 :
5. Strongly agree 0 :

V.5 Online reading assignments helped me understand lectures better.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 2 : **
4. Agree 5 : ***** [3.7 +/- 0.5]
5. Strongly agree 0 :

V.6 Too many online reading assignment questions were asked.
1. Strongly disagree 2 : **
2. Disagree 2 : **
3. Neutral 3 : *** [2.1 +/- 1.0]
4. Agree 0 :
5. Strongly agree 0 :

V.7 I would recommend using online reading assignments in future semesters of
this class.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 1 : *
4. Agree 6 : ****** [3.9 +/- 0.3]
5. Strongly agree 0 :

V.8 Completing the online reading assignments was difficult.
1. Strongly disagree 1 : *
2. Disagree 2 : **
3. Neutral 4 : **** [2.4 +/- 0.7]
4. Agree 0 :
5. Strongly agree 0 :

VI. (Optional.) Please type in any comments you may have regarding
the use of online reading assignments in Physics 205B.
The following are all of the student responses to this question, verbatim and unedited.
"The reason I am neutral towards 'completing the online reading assignments was difficult' is because there we some reading assignments that we difficult, but overall they were good."

"Neutral."

"Online reading assignments were ok. I felt they helped to expose me to a topic which even sometimes confused me even more, and sometimes aided in my understanding! Other times they were just frustrating. It depended on the material and how the book covered it."

"I think interacting in class helped me understand the material better. The reading helped, but most of my concerns were resolved in class."

"Sometimes I felt that the reading assignment was helpful and sometimes it was not. I think it would be interesting to do a post-lecture assignment, where you have to answer questions on what you learned. This way you do not feel so 'blind' going into the subject and you can practice what you learned."
VII. Answer the following statements which may or may not describe 
your beliefs about working on the online homework reports
in this class.

VII.1 Online homework reports were a positive experience.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 4 : **** [3.4 +/- 0.5]
4. Agree 3 : ***
5. Strongly agree 0 :

VII.2 Instructor follow-up on difficult online homework report questions was
valuable.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 3 : ***
5. Strongly agree 4 : **** [4.6 +/- 0.5]

VII.3 Online homework reports motivated me to complete (or try to complete)
problems on my own before coming to class.
1. Strongly disagree 0 :
2. Disagree 1 : *
3. Neutral 2 : **
4. Agree 4 : **** [3.4 +/- 0.7]
5. Strongly agree 0 :

VII.4 Too many online homework report questions were asked.
1. Strongly disagree 1 : *
2. Disagree 3 : *** [2.3 +/- 0.7]
3. Neutral 3 : ***
4. Agree 0 :
5. Strongly agree 0 :

VII.5 I would recommend using online homework reports in future semesters of
this class.
1. Strongly disagree 0 :
2. Disagree 1 : *
3. Neutral 2 : **
4. Agree 4 : **** [3.4 +/- 0.7]
5. Strongly agree 0 :

VIII. (Optional.) Please type in any comments you may have regarding
the use of online homework reports in Physics 205B.
The following are all of the student responses to this question, verbatim and unedited.
"I like how you did a survey on the homework and then attempted to help us better understand the tricky problems in lecture. Also I appreciate you assigning odd problems so we can see and look up the answers so we know if we are on the right track rather than assigning evens, which in my opinion can sometimes cause more harm than good. Ultimately it's up to the individual student to learn the material."

"I'm not sure how my classmates feel about this, but I feel like if the online homework report were multiple choice answers to the questions, and of course saying if we understood the problem or not, students would try harder when doing the problems. I'll admit that sometimes I'd only scan the problem quickly instead of thoroughly doing it. I know it's not right and it doesn't help me if I do that, but when I was extremely busy I would. Sorry."

I think turning in homework assignments would be much more helpful for me. I need that accountability. It is too easy to skim over the problem or think you understand it when you really don't."
Previous posts:

20110725

Education research: post-instruction feedback on laboratory (Cuesta College, Physics 205B, spring semester 2011)

Cuesta College students taking Physics 205B (college physics, algebra-based) at Cuesta College, San Luis Obispo, CA take a mandatory adjunct laboratory. Instead of a conventional set of step-by-step equipment set-up instructions, students are given a specific task to set up, complete and document. For example:
  1. Construct a circuit consisting of a single 9-V battery, and as many Xmas light bulbs (and connectors) as necessary such that there are bulbs with at least three different brightness levels.
  2. Make the appropriate measurements to determine the current and voltage drop of each different brightness bulb when on, in order to calculate the resistance and power dissipated for each unique brightness light bulb (with significant figures).
  3. Discuss how your measurements/calculations demonstrate that there are light bulbs with three different power levels.
(Note that the above task follows an earlier lab where students were not told how to use multimeters, but instructed to tinker and determine their proper handling and use in simple measurements.)

During the last week of instruction, students were given the opportunity to evaluate the laboratory components of the course in an online "Physics Laboratory Learning 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 certain sections were randomly scrambled for each student.
Physics Laboratory Learning Survey
Cuesta College
Physics 205B spring semester 2011 section 30882
(N = 8)

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


II.1 Which of the following best characterizes your
preparation/involvement for lab? Mark all that apply.
Read the directions/review concepts...

1. while doing the lab. 7 : *******
2. immediately before starting the lab. 6 : ******
3. the night before the lab. 2 : **
4. a day (or more) before the lab. 1 : *

II.2 How often did a lab build upon a previous lecture experience?
1. Never 0 :
2. Not much 0 :
3. Sometimes 1 : *
4. Often 5 : ***** [4.1 +/- 0.6]
5. Always 2 : **

II.3 How often did a lab build upon a previous lab experience?
1. Never 0 :
2. Not much 0 :
3. Sometimes 6 : ****** [3.3 +/- 0.4]
4. Often 2 : **
5. Always 0 :


III. Rate the level of your understanding/comprehension for a typical lab.

III.1 Understanding of concepts before coming to lab.
1. None 0 :
2. Very little 3 : ***
3. Some 2 : ** [3.0 +/- 0.9]
4. Much 3 : ***
5. Complete 0 :

III.2 Understanding of concepts after pre-lab discussion, before starting work.
1. None 0 :
2. Very little 0 :
3. Some 4 : ***** [3.5 +/- 0.5]
4. Much 4 : *****
5. Complete 0 :

III.3 Understanding of concepts after completing in-lab work.
1. None 0 :
2. Very little 0 :
3. Some 1 : *
4. Much 5 : ***** [4.1 +/- 0.6]
5. Complete 2 : **

III.4 Understanding of concepts after completing lab report.
1. None 0 :
2. Very little 0 :
3. Some 0 :
4. Much 6 : ****** [4.3 +/- 0.4]
5. Complete 2 : **

III.5 Comprehension of overall lab procedure/instructions.
1. None 0 :
2. Very little 0 :
3. Some 2 : **
4. Much 5 : ***** [3.9 +/- 0.6]
5. Complete 1 : *

III.6 Comprehension of overall lab purpose.
1. None 0 :
2. Very little 0 :
3. Some 1 : *
4. Much 5 : ***** [4.1 +/- 0.6]
5. Complete 2 : **


IV. Typically a lab would help me understand the concepts.
1. Strongly disagree 0 :
2. Disagree 0 :
3. Neutral 0 :
4. Agree 8 : ******** [4.0 +/- 0.0]
5. Strongly agree 0 :


V.1 How much time did you typically spend preparing/studying
before the start of lab (including work on pre-lab assignments)?
1. 15 minutes or less 1 : ****
2. 30 minutes 5 : ******
3. 1 hour 2 : *
4. 2 hours 0 :
5. 3 hours or more 0 :

V.2 How much time did you typically spend working on lab reports
(after completing in-lab work)?
1. 15 minutes or less 0 :
2. 30 minutes 0 : **
3. 1 hour 1 : *****
4. 2 hours 7 : ****
5. 3 hours or more 0 :


VI. (Optional.) Please type in any comments you may have regarding
the laboratory portion of this class.
"It would be nice if the lab instructor went over the pre-labs to show correct or incorrect answer."
Previous posts:

20110724

Education research: SASS and student learning outcomes (spring semester 2011)

Student achievement of course learning outcomes are assessed by administering an Student Assessment of Skills Survey (SASS), a five-point Likert scale questionnaire (Patrick M. Len, in development) to Astronomy 210 students at Cuesta College, San Luis Obispo, CA. This is a one-semester, introductory astronomy course (with an optional adjunct laboratory), and is taken primarily by students to satisfy their general education science transfer requirement.

The SASS is administered online during the last week of instruction, to be completed before the final exam.

The results for SASS from this semester are compiled below. Values for the mean and standard deviations are given next to the modal response category for each question. Also listed is the percentage of students who have self-assessed themselves as having successfully achieving a learning outcome (responding "average," "above average," or "excellent") as opposed to not achieving success with a learning outcome (responding "very poor" or "below average").

Cuesta College
Student Assessment of Skills Survey (SASS)
Astronomy 210 spring semester 2011 sections 30674, 30676

The questions below are designed to characterize your achievement of each
of the learning outcomes by filling in a bubble on the rating scale
provided to the right of each statement.

Mark the level of achievement that best describes your learning at the
completion of the course.

1. Predict positions and cycles of stars, using a starwheel.
(Achieved: 90%, unachieved: 10%)
1. Very poor 0 :
2. Below average 7 : *******
3. Average 30 : ****************************** [3.6 +/- 0.9]
4. Above average 19 : *******************
5. Excellent 16 : ****************

2. Explain sun cycles and seasons.
(Achieved: 92%, unachieved: 8%)
1. Very poor 0 :
2. Below average 6 : ******
3. Average 29 : ***************************** [3.6 +/- 0.9]
4. Above average 23 : ***********************
5. Excellent 14 : **************

3. Explain and predict lunar phases and times.
(Achieved: 94%, unachieved: 6%)
1. Very poor 2 : **
2. Below average 2 : **
3. Average 29 : ***************************** [3.6 +/- 0.9]
4. Above average 28 : ****************************
5. Excellent 10 : **********

4. Relate planets in the sky to a solar system map.
(Achieved: 90%, unachieved: 10%)
1. Very poor 1 : *
2. Below average 6 : ******
3. Average 35 : *********************************** [3.4 +/- 0.8]
4. Above average 24 : ************************
5. Excellent 6 : ******

5. Explain differences between models of planetary motion.
(Achieved: 89%, unachieved: 11%)
1. Very poor 2 : **
2. Below average 6 : ******
3. Average 29 : ***************************** [3.4 +/- 0.9]
4. Above average 28 : ****************************
5. Excellent 7 : *******

6. Explain evidence for the heliocentric model of planetary motion.
(Achieved: 83%, unachieved: 17%)
1. Very poor 1 : *
2. Below average 11 : ***********
3. Average 34 : ********************************** [3.3 +/- 0.9]
4. Above average 16 : ****************
5. Excellent 10 : **********

7. Describe how optical telescopes work.
(Achieved: 81%, unachieved: 19%)
1. Very poor 3 : ***
2. Below average 11 : ***********
3. Average 31 : ******************************* [3.3 +/- 1.1]
4. Above average 15 : ***************
5. Excellent 12 : ************

8. Describe different powers of optical telescopes.
(Achieved: 81%, unachieved: 19%)
1. Very poor 2 : **
2. Below average 12 : ************
3. Average 26 : ************************** [3.4 +/- 1.0]
4. Above average 21 : *********************
5. Excellent 11 : ***********

9. Explain which telescopes should be funded based on relevant criteria.
(Achieved: 88%, unachieved: 13%)
1. Very poor 1 : *
2. Below average 8 : ********
3. Average 23 : *********************** [3.7 +/- 1.0]
4. Above average 21 : *********************
5. Excellent 19 : *******************

10. Explain how stars produce energy.
(Achieved: 83%, umachieved: 17%)
1. Very poor 1 : *
2. Below average 11 : ***********
3. Average 27 : *************************** [3.4 +/- 1.0]
4. Above average 22 : **********************
5. Excellent 11 : ***********

11. Explain the relationship between star brightness and distances.
(Achieved: 92%, unachieved: 8%)
1. Very poor 1 : *
2. Below average 5 : *****
3. Average 19 : *******************
4. Above average 23 : *********************** [3.9 +/- 1.0]
5. Excellent 24 : ************************

12. Predict the size of a star based on brightness and temperature.
(Achieved: 97%, unachieved: 3%)
1. Very poor 0 :
2. Below average 2 : **
3. Average 22 : **********************
4. Above average 25 : ************************* [3.9 +/- 0.9]
5. Excellent 22 : **********************

13. Explain different stages a star will go through, based on its mass.
(Achieved: 83%, unachieved: 17%)
1. Very poor 3 : ***
2. Below average 9 : *********
3. Average 24 : ************************
4. Above average 23 : *********************** [3.5 +/- 1.1]
5. Excellent 13 : *************

14. Explain evidence for the shape/size/composition of our Milky Way galaxy.
(Achieved: 85%, unachieved: 15%)
1. Very poor 1 : *
2. Below average 10 : **********
3. Average 28 : **************************** [3.5 +/- 1.0]
4. Above average 20 : ********************
5. Excellent 13 : *************

15. Explain evidence for how our Milky Way galaxy came to be.
(Achieved: 80%, unachieved: 20%)
1. Very poor 0 :
2. Below average 14 : **************
3. Average 25 : ************************* [3.3 +/- 0.9]
4. Above average 24 : ************************
5. Excellent 6 : ******

16. Explain how the speed of light affects observations of distant objects.
(Achieved: 88%, unachieved: 13%)
1. Very poor 0 :
2. Below average 9 : *********
3. Average 23 : ***********************
4. Above average 21 : ********************* [3.7 +/- 1.0]
5. Excellent 19 : *******************

17. Explain evidence for the expansion of the universe.
(Achieved: 85%, unachieved: 15%)
1. Very poor 2 : **
2. Below average 9 : *********
3. Average 28 : **************************** [3.4 +/- 1.0]
4. Above average 22 : **********************
5. Excellent 11 : ***********

18. Describe characteristics of the universe a long time ago.
(Achieved: 83%, unachieved: 17%)
1. Very poor 2 : **
2. Below average 10 : **********
3. Average 31 : ******************************* [3.3 +/- 0.9]
4. Above average 23 : ***********************
5. Excellent 6 : ******

19. Explain evidence for how our solar system came to be.
(Achieved: 88%, unachieved: 13%)
1. Very poor 1 : *
2. Below average 8 : ********
3. Average 38 : ************************************** [3.3 +/- 0.8]
4. Above average 18 : ******************
5. Excellent 7 : *******

20. Describe key features of terrestrial planets.
(Achieved: 92%, unachieved: 8%)
1. Very poor 1 : *
2. Below average 5 : *****
3. Average 23 : *************************
4. Above average 26 : ************************** [3.7 +/- 0.9]
5. Excellent 17 : *****************

21. Describe key features of jovian planets.
(Achieved: 93%, unachieved: 7%)
1. Very poor 1 : *
2. Below average 4 : ****
3. Average 25 : *************************
4. Above average 27 : *************************** [3.7 +/- 0.9]
5. Excellent 15 : ***************

22. Explain why Pluto is not currently categorized as a planet.
(Achieved: 94%, unachieved: 6%)
1. Very poor 0 :
2. Below average 4 : ****
3. Average 22 : **********************
4. Above average 24 : ************************ [3.9 +/- 0.9]
5. Excellent 22 : **********************

23. Describe plausible requirements for life.
(Achieved: 93%, unachieved: 7%)
1. Very poor 1 : *
2. Below average 4 : ****
3. Average 22 : **********************
4. Above average 28 : **************************** [3.8 +/- 0.9]
5. Excellent 17 : *****************

24. Explain difficulties in investigating the possibility for extraterrestial life.
(Achieved: 93%, unachieved: 7%)
1. Very poor 1 : *
2. Below average 4 : ****
3. Average 21 : *********************
4. Above average 28 : **************************** [3.8 +/- 0.9]
5. Excellent 18 : ******************


Of the 24 student learning outcomes in the SASS, 17 were self-reported as being achieved by at least 85% of students, listed below in order of decreasing success:
12. Predict the size of a star based on brightness and temperature. (97%)
3. Explain and predict lunar phases and times. (94%)
22. Explain why Pluto is not currently categorized as a planet. (94%)
21. Describe key features of jovian planets. (93%)
23. Describe plausible requirements for life. (93%)
24. Explain difficulties in investigating the possibility for extraterrestial life. (93%)
2. Explain sun cycles and seasons. (92%)
11. Explain the relationship between star brightness and distances. (92%)
20. Describe key features of terrestrial planets. (92%)
1. Predict positions and cycles of stars, using a starwheel. (90%)
4. Relate planets in the sky to a solar system map. (90%)
5. Explain differences between models of planetary motion. (89%)
9. Explain which telescopes should be funded based on relevant criteria. (88%)
16. Explain how the speed of light affects observations of distant objects. (88%)
19. Explain evidence for how our solar system came to be. (88%)
14. Explain evidence for the shape/size/composition of our Milky Way galaxy. (85%)
17. Explain evidence for the expansion of the universe. (85%)

However, 7 student learning outcomes were self-reported as being achieved by less than 85% of students, listed below in order of decreasing success:
6. Explain evidence for the heliocentric model of planetary motion. (83%)
10. Explain how stars produce energy. (83%)
13. Explain different stages a star will go through, based on its mass. (83%)
18. Describe characteristics of the universe a long time ago. (83%)
7. Describe how optical telescopes work. (81%)
8. Describe different powers of optical telescopes. (81%)
15. Explain evidence for how our Milky Way galaxy came to be. (80%)

As per the ACCJC (Accrediting Commission for Community and Junior Colleges), results from this assessment tool will be used for course/program improvement by increasing emphasis on these lowest seven student learning outcomes in instruction in future semesters.

Previous post:

20110723

Presentation: Newton's third law

Recall that there are two types of motion (constant and changing), and two types of net forces (zero and non-zero), addressed by two laws: Newton's first law and second law. As we'll see, Newton's third law has nothing to do with motion or net force, but a fundamental property of force itself, regardless of the resulting motion or net force. In a sense, something to do with symmetry.

Let's first address a fundamental property of any force before looking at how to recognize when and how to implement Newton's third law.

All forces are the interactions between two objects. In this case, the dog and owner are using the rope tension force in order to interact with each other. Because two objects are involved, then there will be two different, but valid viewpoints of this interaction--from the dog's point of view, and the owner's point of view.

If there aren't two objects involved, then there is no interaction. If there is nothing on the other side of that cable, then the plane isn't interacting--exerting forces on--anything else. An interaction always involves two objects, each exerting a force on each other.

Did you learn trigonometry using SOH-CAH-TOA? For Newton's third law, we'll use a similar-looking mnemonic from Benjamin Crowell (Fullteron College, CA).

This three-part checklist is used identify if two forces are related via Newton's third law:
  • POF: Pair of Opposite Forces?
    Are the two forces aren't pointing in opposite directions?
  • OST: Of Same Type?
    Are the two forces the same type of interaction (weight, normal, tension, static friction, kinetic friction, etc.)?
  • ITO: Involving Two Objects?
    Are there explicitly two objects interacting with each other?
If these two forces in question satisfy all three parts of the POF-OST-ITO checklist, then Newton's third law applies. However, if even one part of the POF-OST-ITO checklist fails, then Newton's third law does not apply to the two forces in question.

Only after knowing when Newton's third law applies, let's discuss how Newton's third law applies.

On the surface, this "action-reaction" equation seems like a trivial statement, but it embodies each part of the POF-OST-ITO checklist:
  • POF: Pair of Opposite Forces?
    Due to the negative sign, two forces are in opposite directions.
  • OST: Of Same Type?
    Both forces must be w = w, N = N, T = T, fs = fs, fk = fk, etc. on either side of the equation.
  • ITO: Involving Two Objects?
    The two interacting objects exerting a force on each other are in the subscripts on either side of the equation.

Remember, because an interaction involves two objects, there will be two slightly different, but equally valid descriptions of the same force. This is the fundamental statement of symmetry in Newton's third law!

Let's try to distinguish between forces that are equal in magnitude, but opposite in direction due to Newton's first law, versus those forces that are equal in magnitude, but opposite in direction due to Newton's third law. In this example, this stack of books is stationary on a person's head.
According to Newton's first law, the normal force of the person's head on the stack of books is equal in magnitude and opposite in direction to the:
(A) normal force of the stack of books on the person's head.
(B) weight force of Earth on the stack of books.
(C) (Both of the above choices.)
(D) (Neither of the above choices.)
(E) (Unsure/lost/guessing/help!)

According to Newton's third law, the normal force of the person's head on the stack of books is equal in magnitude and opposite in direction to the:
(A) normal force of the stack of books on the person's head.
(B) weight force of Earth on the stack of books.
(C) (Both of the above choices.)
(D) (Neither of the above choices.)
(E) (Unsure/lost/guessing/help!)

20110722

Astronomy in-class activity: planet-hunting

Astronomy 210 In-class activity 6 v.11.06.21, fall semester 2011
Cuesta College, San Luis Obispo, CA

Students find their assigned groups of three to four students, and work cooperatively on an in-class activity worksheet to determine where in the sky each naked-eye planet will be observed on a given date (here, September 1, 2011).




Previous posts:

20110720

Physics presentation: interactions

Yes, beer is good. (Perhaps there's an extra letter in this sign that shouldn't be there...) But if you walked into a microbrewery with a wide selection of fine beers on tap, how do you know which beer is good? You don't have the time, money, or wherewithal to order and drink a pint of each different type of beer. So what do you do?

Some microbreweries offer what they call a "Brew-Ski," where a small sample of each of their beers on tap is placed, literally, on a "ski," in order to introduce you to their line-up. (These samplers are sometimes called "flights.")

Sampling individual beers separately is fine, but what would happen if all the different beers from a "Brew-Ski" were combined into the same glass? Is this so wrong?

Which leads us to our discussion of different types of mechanical interactions--forces. Since we will investigate the details of these forces later in this (algebra-based college physics) course to, let's settle for the "Brew-Ski" approach, where we'll look at a selection of important forces, briefly. And since many situations in the real world involve more than one type of force acting on the same object at the same time, we'll consider the result of combining different types of beers--that is, forces--into a net force.

Here's our "Brew-Ski" force line-up. Remember, we'll go into more detail on each of these as the course progresses, but for now, this will just be an introductory tasting.

Weight, or the force of gravity, is the easy-cheesy force. For our purposes its magnitude is always equal to the product of the object's mass m, and the gravitational strength constant g ("acceleration due to gravity"), regardless of the motion or location of the object. (Movie link: "Biggest Cliff Jump on Youtube (100+ Feet).")

The normal force is the supporting contact force exerted by a surface. Its magnitude can vary from zero (no or barely any contact) up to ∞, but practically speaking a surface can only exert up to a maximum value, depending on structural integrity of the underlying material, until it fails. In this case, the floor can exert a normal force to support the weight of the contents of the room, but only up to when the room gets filled with too much water. (Movie link: "Collapsing floor by filling room with water.")

The tension force is the force exerted along a string, rope, or cable. Its magnitude can vary from zero (slack or barely pulling) up to ∞, but practically speaking a rope will have a maximum value, depending on the strength of its material/construction, until it fails. Here, a towing "snatch" strap exerts a tension force to pull on a stuck vehicle, but only up to when it is pulled too much. (Movie link: "Broken snatch strap.")

The static and kinetic friction forces apply to unsticking or subsequently sliding an object across a surface, respectively. The magnitude of the static friction force can vary from zero (no or barely trying to unstick an object) up to a maximum value, at which point the object becomes unstuck, and just begins to move. The magnitude of the kinetic friction force magnitude is always a constant value, once the object is already unstuck and moving. Note that the maximum magnitude of "stiction" (static friction) is greater than the magnitude of "sliption" (kinetic friction). (Movie link: "Static vs. Sliding Friction.")

So much for the "Brew-Ski" overview of different types of forces. Let's move on to more complex situations, and the tools used to handle them.

Most everyday situations involve more than one type of interaction happening at the same time--consider the forces acting on the board: weight, normal force, tension, static friction force (assuming that the girl is not sliding off of the board), and kinetic friction force (assuming that the board is already sliding across the sand).

Each force is represented with a vector--the magnitude (length) represents the strength of the interaction, and the direction represents, well, the direction of the force exerted. Typically many forces, all acting on the same object can be depicted on a free body diagram.

Forces all acting on the same object all add together to result in a net force (Fnet), which is what the summation operator signifies. Since mathematically vectors can be broken up into x- and y- components, and then separately added together to find the resulting x- and y- components of the net force.

Looking ahead, how many Newton's laws are there? (Three.) But there are only two ways to classify motion--constant, or changing, corresponding to Newtons first law, or second law. Or only two ways to classify net force--zero, or non-zero, corresponding to Newton's first law, or second law.

So if there's only two types of motion, and two types of net forces, what's up with Newton's third law? As it turns out, Newton's third law has nothing to do with motion or net force, but something else entirely, something much more universal and encompassing than considering a particular type of motion or net force...