20180122

Online reading assignment: flipped classroom, electromagnetic waves, reflection and refraction

Physics 205B, spring semester 2018
Cuesta College, San Luis Obispo, CA

Students have a bi-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.

The following questions were asked on reading textbook chapters and previewing presentations on electromagnetic waves and redirecting light (reflection and refraction), along with advice from students from the previous semester, and videos on the flipped class mode of instruction used in this course.

To convince yourself that the frequency of the wave remains constant in either material, try this with a friend--when a crest appears from the left edge of the screen, say 'in.'  When a crest disappears at the right edge of the screen, have your friend say 'out.'

Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.
"There are different types of light on the spectrum starting with low frequencies like radio waves to high frequencies like gamma rays. Also, light changes speed and wavelength when it travels through different materials."

"The relationship between the speed, frequency, and wavelength of light as it passes through different materials. As speed increases, the wavelength increases with it, but the frequency remains constant."

"Visible light is just a portion of the electromagnetic spectrum and can change speed as it passes through different media."

"Snell's law deals with light traveling through two different mediums and finding the corresponding index of refraction between the two mediums and the angle that light refracted at when it travels through the second medium. Lastly if light is going from fast to slow it bends toward the normal and if it is going slow to fast it bends away from the normal."

"The 'fast-to-slow, bend towards normal' mnemonic you could use for Snell's law really helped me (especially since it was right next to the image)."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.
"How to recognize how wavelength, velocity and frequency are related, although I do understand that the wavelength is dependent on speed of the medium and the frequency of the source of light."

"How is bending light in refraction different from bouncing light in reflection?"

"I need help with the index of refraction."

"I found the introduction to refraction more confusing. I could use an explanation on how light bends and how to use that information in equations."

"I think I need some more practice on Snell's law. I think I understand it, but I'm not quite sure."

No ducks were harmed in the taking of this photograph.
Consider light traveling either through air (nair = 1.0) or through water (nwater = 1.33). Light travels with the faster speed through:
air.  ******************************* [31]
water.  [0]
(There is a tie.)  * [1]
(Unsure/guessing/lost/help!)  [0]

A ray of light has an incident angle of 60° in air, and a transmitted angle of 36° in plastic. Determine what happens to each of the following parameters as the light passes from air into plastic.
(Only correct responses shown.)
speed v: decreases [75%]
frequency f: remains constant [63%]
wavelength λ: decreases [56%]

For the above example of light incident in air being transmitted into plastic, __________ has the greater index of refraction.
air.  ****** [6]
plastic.  ************************** [26]
(There is a tie.)  [0]
(Unsure/guessing/lost/help!)  [0]

The faint reflected ray is not quite visible here, and yes, this picture is flipped left-to-right, but convince yourself that this doesn't change any of the angles and indices of refraction in Snell's law.
A ray of light has an incident angle of 20° in plastic, and a transmitted angle of 29° in air. Determine what happens to each of the following parameters as the light passes from plastic into air.
(Only correct responses shown.)
speed v: increases [63%]
frequency f: remains constant [63%]
wavelength λ: increases [66%]

For the above example of light incident in plastic being transmitted into air, __________ has the greater index of refraction.
air.  ************************ [24]
plastic.  ******** [8]
(There is a tie.)  [0]
(Unsure/guessing/lost/help!)  [0]

State your preference for denoting the inverse sine operation.
Arcsin.  * [1]
sin–1.  **************************** [28]
(No preference.)  *** [3]
(Unsure/guessing/lost/help!)  [0]


Explain what is different about homework in a flipped class.
"Homework is done at home to help introduce me to the concept but it is cemented in class."

"In a flipped class, homework is reading and covering work that is to be discussed in the next class. Material that was not well understood is then discussed more thoroughly."

"A flipped class is more consistent of lecturing on the things that the students did not understand based on the previous reading and given homework. Rather than overall lecturing about everything. Rather, staying on the key topics that student need more help with."

"The flipped classroom homework presents material a student should be familiar with and presents topics to be covered in class."

"Homework is done mostly IN class, and lectures are done online, outside of class. So in class we go over things people are stuck on, and more examples explaining some confusing topics."

"The homework is where you are introduced into the material as opposed to practice the material."

Describe where/when most student learning occurs in a flipped class.
"Most learning will be done outside of class. Primarily before class starts with reading/homework, and after class with going to office hours. In a conventional class most learning is done during class, where students usually come to class with no reading done beforehand."

"Learning happens at home more so in a flipped class and it is dependent on the student to decide what they understand or don't understand and might need more help with when in comes lecture time. In a conventional classroom you have more learning done within the class. Or at least attempted learning."

"In the flipped class, learning is done primarily in class with peers and the instructor, working out problems. Conventional classes have most of the learning done outside of class on their homework."

"I think it is during class when going through examples after having seen the lessons on the blog. It completes the gaps and all the misunderstanding and confusion."

"Basic knowledge of the concept should be learned at home or away from the classroom. Application of that knowledge can be learned in the classroom."

"It will vary based on the individual's learning style. For some learning will be most effective when watching lecture material before class, but for others it will come during face to face problem solving time with the professor."

Pick one piece of student advice from the previous semester, and discuss why you agree (or disagree) with it.
"'Just make time to do the online homework and reading. It really isn’t that bad or difficult. Just quit procrastinating and you'll be fine.' As someone who took your last class I completely agree. It isn't hard most of the time, you just have to remember to do it."

"'Go to lecture, lab, and do all the required work like you would normally do to succeed in any course.' It worked for me last semester in Physics 205A."

"'Attend class.' Simple, yet important. Not only for receiving points. But it will help with covering the things that probably not only you but other students in the class did not understand from the reading. This helps to not get behind on the topics as some can be more challenging than others."

"'Practice prior year's quizzes and exams! Also, really know each equation, what it is used for, and what the symbols in the equation stand for.' This is what helped me a TON in preparing for the exams, and I can definitely say I did very well by following this approach to studying. Practice makes perfect, and as long as you understand the concepts and know what each symbol stands for, you should be golden."

"'Re-read the blogs and go over the quizzes and homework.' I agree with this because re-reading the blogs from last semester really helped me understand things more clearly."

"'You've got it! Stop freaking out, be constant and anticipate!' Not sure if I wrote that or not...but if I did, I am still agreed with myself! Taking it step by step even if I am a bit behind, I should keep going."

"One of the students recomended getting a tutor, but I disagree with the idea of a tutor in a flipped classroom. In a flipped classroom the teacher is the tutor, helping you with questions you have along the way."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Could you please discuss independent and dependent parameters and the equations that come with it."

"Does a medium's density change the speed of light through it?" (Yes, typically the denser a (transparent) material is, the slower light will travel through it. In the space between atoms, light travels with the same speed as in vacuum (as there is nothing in the space between atoms), but as light encounters each atom, the atom absorbs the light and begins to oscillate, and then the re-emits light to travel to another atom. This causes a "lag time" that effectively decreases the speed that light will take to travel through the material (as it continuously needs to be absorbed and re-emitted), and if the material is dense either due to closer spacing between atoms, or heaver atoms, then the speed of light will be slower through this material.)

"Is it a big problem waiting until the night before to do assignments?" (Not if you remember to do the online assignments before the deadline.)

"Do we need to buy the book?" (It's not the greatest book ever, but you'll need it for the background information and problem sets. Unless you have mad Google skills to look everything up on your own.)

"I'm excited for this class. The material is much denser than last semester, which, in my mind, makes it more interesting."

"I am excited to see how this semester will change the way that I understand how the world works!"

"I'm looking forward to this semester!"

"I would just like to say, your flipped classroom had a great impact on me, so much so that when I went to biology this semester, I was quite disappointed to learn that it's not flipped and that it would just be lectures and exams. I feel like in your class I really learned and found out what worked for me."

"Ramen or soba?" (In Hawaii, saimin (細麵) rules, which has Chinese noodles in a Japanese broth, with various Filipino, Portuguese, Hawaiian, and Okinawan ingredients added to it. It's even on the menu at McDonald's in Hawaii. #imlovinit)

No comments: