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February 13, 2015


I've made a small attempt to flip my classroom this year. I believe that when the students are in the room together (and with me), they should be interacting with me and with each other. So when I want to introduce the students to a new concept, or develop some ideas, equations, etc. that we discovered during inquiry in lab, I assign them to watch a video. Then the next day we use TIPERs or traditional practice problems to apply what they learned in the video. I don't have time to create every video that I need them to watch so I am grateful to those who have already created high-quality videos. I have been a fan of Dan Fullerton's APlusPhysics videos since I discovered them early this year. Recently a student discovered some other videos on her own and sent me the link in a message.

These physics lessons can be found at and they are made by a high school teacher from Maryland named Yau-Jong Twu.  I've only had time to look at a few of the videos, but I was impressed by what I saw. Ms. Twu writes incredibly neatly on a piece of paper and uses a yellow pencil to direct the viewers' attention. Unlike my videos, which are usually made in haste in one 10-minute take, hers have good production value. She has a nice title in the beginning and suggestions for when the viewer can pause the video to make his or her own calculation.  She draws images and diagrams using a ruler and a protractor.  And she occasionally uses props to help illustrate her point.  In the video entitled "Angular Momentum and Angular Momentum of a Point Mass," she uses two small Lego people to demonstrate how an object moving in a straight line has angular momentum.
She shows how the Lego person in the white hat has to turn his head to follow the moving Lego person in the black hat.  Thus, the moving Lego person has angular motion relative to the stationary person, and thus angular momentum relative to him.  Genius!  I never thought to describe it that way before*. She continues to derive an expression for the angular momentum of an object moving in a straight line, and does so in a very clear, coherent way.
Many of her videos involve ranking tasks, or other conceptual questions.  Another one of my favorites is titled "Spheres Going Up Inclines with Different Friction." Two spheres are rolling without slipping toward two different hills.  One hill has friction, one does not. She asks the viewer to predict which sphere will go higher up the hill. She pauses for 8 seconds, displaying a prompt for the viewer to stop the video if he or she needs more time to think.
Ms. Twu then continues to explain the physics. This is exactly the type of comparison task (found in the TIPERs books**) that elicits conceptual reasoning and fosters deep conceptual understanding.  

I've only just discovered these videos, but I plan to post various individual videos to each unit web page for the students to use either to develop concepts, or simply for review if they need it.  And I plan to post a link to so students can search out her videos for any topic they need. 

And the student who discovered these got a free "Late Homework Coupon" for her efforts.   

*Perhaps I shouldn't admit that, given that I have been teaching angular momentum for 25 years.  So I'll blame it on the fact that I don't have children, and thus do not have extensive experience with Lego people.
**Links to sources for the TIPERs books can be found on my Teacher Training Site, on the "Book Resources" page.  

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