Optics reflection refraction

Week eleven began with the United Nations Day holiday, dropping the Monday lead optics video. Wednesday drove straight into reflection and refraction using the mirror cart rolled to the front of the classroom.



The class followed the usual arc into lenses.

For the lab on Thursday I pulled graduated cylinders from the cabinets - a stash I had not known about prior to this term. I upped the number of tall cylinders, which provided better data, and dropped the number of beakers. The refracted penny was kiboshed due to the pans being too brittle. There was little loss in this choice. 

Jasmine, Sanjay, and Kamaloni "Kai"

The 8:00 section started a little late due to students rolling in late. 

Following suggestions from prior terms I omitted all mention of the mathematical model to be used, and made sure that the word slope did not appear on the board. This was the board at the end of the 8:00 lab. I put no equation on the board. The students obtained linear data. I told them to pick the equation. Two of the students drew a complete blank. One student had a table with i₁ and o₁. The student entered o₁~pi₁. The student then had a value for p. When I asked what is p, the student could not answer. I realized that the question was vague. I rephrased, in math class what would we call p? None of the three students seemed to comprehend my question. Like a broken record I returned to the theme that "math class cannot teach you mathematics, it is not your fault." 


I then built the diagram on the right side of the board where I tried to elucidate the meaning behind the pieces of a linear equation. None of the students ever did realize that p was the slope, not until I specifically used the word myself. Students do not understand how equations work, not at some fundamental conceptual level. The approach of 30 problems even numbers only teaches NOTHING. There is no comprehension, no retention, no understanding. 

Myena

This term I focused the procedure for the apparent depth on measuring down from the top of the water using the edge of the table. Yes, one could measure up from the table to the top of the water, but students invariably lose track of what they are measuring and measure to the top of the container. This approach at the table's edge works much better. I am reminded that in stand up comedy the exact placement of a word, and the choice of the word, makes all the difference between funny and not. Labs are subtle beasts. Measure up, and the students mess up. Measure down, and they all get the depth right. Small change between funny and not, between done right automatically and done wrong. 

Myean, Tommy, Alexander



Jocela, Fredson, Kiora measuring object and image distance for a mirror

Joe Scott and Ann "Lovery" Loverina

Sean and Reagan





In the 11:00 I mentioned that the "slope" of the apparent depth experiment is 1.333, the index of refraction for water. 

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