Day 4

3:29 P.M.

Block 1 (AP Physics C)

This is my third year of teaching AP Physics as a second year physics class, and I think I am more conscientiously seeking a balance between moving on to new AP material and reviewing old material to keep students current.

Today I decided to keep things a little more on the fun side. I had them share their blogs with me via a google form  ( (I know I have access to the back end as an admin on blogger if they let me, but I like to build a splash page for professional development purposes)

To begin I had them review basic formulas on whiteboards I simply had them write down the formulas for KE, Gravitational Potential Energy, and Elastic Potential Energy (assuming Hooke’s Law)  and hold them up.

Many of them were a bit rusty and it was a great way to get us consistent on notation. For example some write Kinetic Energy as KE, others as Ek.

This was a discussion that took about 20 minutes because I did a bit of lecture. I did want to deconstruct AP expectations. I explained that they would have to memorize formulas for the MC section. I explained how I scaffold them to this expectation through the year by making the exam more difficult each time.

For the remaining 50 minutes We did a mini-challenge where I had students show me 1 J of energy in as many ways as possible. I left a bunch of toys (tennis balls, bouncy balls, masses, spring scales etc)

It was actually quite fun and gave me a lesson in classroom management. One of the students started volleying a tennis ball to another, and I told them to calculate how much energy the ball has as it moves based on its speed and mass.

They came up with this:

Screen Shot 2013-08-26 at 3.50.53 PM

Clearly there is some work to do, but this is exactly why this exercise is useful, as it allows me to see what students have forgotten over the summer. One of my more successful groups did the following:

Screen Shot 2013-08-26 at 3.38.16 PM Screen Shot 2013-08-26 at 3.38.25 PM

which of course is reassuring, but it is clear we need to review Hooke’s Law.

Block 2,4  (Physics 1,2)

Today, I finally got a chance to do an Earth-Moon Lab with my students. I changed a couple of things in the process this year in that all students are using blogger.

We began class by having students share their blog url with me via the google form.

Next I tried a very simplified version of Dan Meyer’s 3-Act Tasks .

Act 1)


What questions does this bring up?

I am a little new at 3-Act tasks, and so I acted as a recorder cherry-picking questions that led students to the question I wanted them to answer:

Here are some of the questions they came up with?

  • Why aren’t there any words?
  • Why are the Earth and moon so close together?
  • Wait. Are these the right size? (I had them dig deeper here since the correct answer is “no”)
  • Shouldn’t they be farther apart?

We had a discussion and for both blocks we narrowed the question down to “How far apart should these cutouts be if we want an accurate scaled distance?”

Act 2)

I asked them to guess and show me with their cut our Earths and moons how far apart they would put them to scale.  Out of 60 students, I had one who had a reasonable estimate (he was also the one who finished the bonus round which I will discuss in a bit). I had them photograph this scaled model to post to their blogs later.

I actually forgot to ask students what information would be helpful in answering this question in my second block. Oddly enough Block 2 did better without the information. I think our schedule which had me seeing my block 4 class at the end of the day might have my students sluggish since it is a new school year.

With block 4 I did ask them, what information would be helpful in solving this problem. They decided on the following:

  • The real distance from the Earth to the Moon
  • “How big the Earth and Moon are”

It was interesting teasing the meaning out of this as students finally settle on both diameter and circumference.

I then had them look up the diameters and distances to figure it out. Some got it right away. Others struggled, but what made me happy is that all of them were engaged and on task the whole time.

The answer they ended up getting was around 30 Earths which is similar to last year.

Act 3)

I wanted to have the students go a bit further, so for ones who finished I had them do a new problem. I had a penny represent the Earth. I then had them show the distance of the sun to scale. For the curious, the answer ended up being around 40 meter sticks according to one student.


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