November 17: Test review

Today we tried something new, which I think worked out very well. Instead of covering problems one-by-one on the board, the students were split into six groups (roughly four per group). Each group had a set of small problems or tasks to work on. After about ten minutes, the tasks were rotated (via groups moving to different tables). Overall it seemed that the students were a lot more engaged. They were able to discuss the problems with each other more openly, and the teacher and I were free to assist groups as needed. I noticed a few students that were less motivated to participate, but it was more a matter of their attitude than the activity. The reaction from the students afterwards was very positive. As discussed with the teacher, some improvements could be made. The main problem was that some stations (those requiring math) took too much time to complete the task.

Drawings

It has come up a few times now, while doing boardwork, that the students get a little frustrated if drawings aren’t done precisely (no freehand!). This is entirely because they were taught this way by us when we covered usage of the ruler and protractor. While it is nice to see them start to appreciate some rigor and precision, I worry that we’ve made them distrust the freehanded drawing too much. Also, I don’t want to draft every drawing I make on the board with painstaking care (call me lazy, it’s true, but it’s also a time commitment). The big issue I see though, is that very often in real life you have to deal with freehand drawings. The students should be comfortable with a cartoon that doesn’t portray every scale and angle precisely, but is used to emphasize a point. I think it is important to clarify when it is acceptable to freehand and when extra time and care is needed to draft something with more fidelity.

October 17: More Gravity HW review

This block was spent covering the gravity homework. There was still some confusion about calculator usage and many calculating errors. I mostly paced the room, helping students one-on-one while the teacher reviewed. After spending so much time on calculator usage, I’m of the opinion that some sort of primer should be made as a handout. Perhaps a one page handout on how to use a calculator, covering the main functions that will be needed. Similarly to the discussion on October 14, give the function, common ways its presented on different calculators, a few examples of how to enter it, and maybe a few self tests. Another handout could be made for basic math concepts that will be used frequently in the class, such as order of operations, commutativity, manipulating a formula, understanding a formula, conversions (multiplying by 1), rounding, and scientific notation. A third might focus on units, although this is something that is and should still be covered in class. A few reasons why these handouts are a good idea:

• these would give students a good reference sheet
• more class time can be dedicated to physics
• helps students learn to self teach
• sets a baseline for expectations. its clear for the students what they need to know
• even if the handout is not enough, it introduces the concepts. when they do come for help, they’ll be a little further along than they would be otherwise.

The best use of class time is to say the things that everybody needs to hear. Situations where there is a large spread in student abilitiy and/or understanding might be more effectively handled by self teaching (reading assignments and HW) and after school assistance. The students who get it can dedicate their time to other things (and don’t get bored). Those who don’t get it will unfortunately will be burdened with more work, but they will also be able to take the time they need without worrying about their classmates.

October 14: Gravity HW review

Alexis observed class today. The goal was to spend 10-15 minutes going over the homework problem and then to start into the light reflection lab. What actually happened was, since the students were very confused about the homework, nearly all of the time was spent covering how to use a calculator and a little time was spent on units. Despite taking up so much time, I felt that I did a good job of organizing the discussion and getting the points across. Alexis’ review was largely favorable as well. A lot of confusion had to do with calculator usage, order of operations, and units. 

I explained the scientific notation button (x10n), negative button (+/-), and square button (x^2) by drawing a table. In the table I wrote down the desired function, the different ways it shows up for various calculators, how it should be entered, and an example to try. For units I just showed how they cancel out, mentioned that forces are measured in Newtons, and stressed that if you know what you are calculating, you can check yourself by making sure the units of your answer are correct. I also mentioned a simplified rule for rounding (truncating your answer to have the same number of digits as your inputs). 

At the end of class, two more problems were assigned. Essentially the same thing, but with different masses and distances. Two pages on light were assigned for reading.

October 13: Gravity - Center of Mass, Newton’s Law of Gravity

Students had assigned reading covering center of mass and Newton’s law of gravity. Discussion in class focused on these topics, finding the center of mass of various objects and starting into some math. I thought this went pretty well. No particular comments. For homework, students were asked to find the force of gravity on earth from the sun. The equation as well as all the constants were given.

October 7: Gravity - Ball Drop Activity

Today we showed the class a Bill Nye segment demonstrating why planets travel in circular orbits. The class seemed to enjoy the video, and it was a good segue into the ball drop activity. Overall I felt that the class was much more focused today. The students really got involved with the ball drop activity. There was a lot of discussion about which objects would fall first and why. Good opportunity to discuss human error and the importance of multiple trials.

Earlier in the class, a student asked me if we had really gone to the moon (in connection with the Bill Nye video), and so I was really hoping to show the Apollo video demonstrating a hammer and feather falling at the same time. Unfortunately, we ran short on time (Friday block is only 45 minutes) but I told the student to search for the video. Monday I’ll see if he took my suggestion (he did).

October 5: Retrograde Motion Activity

At the end of the last class, I showed the class retrograde motion using the software (Stellarium), but I did not explain how it happened. I was hoping a few students might think about it outside of class, and perhaps search online for an explanation (there was no indication that anybody actually did this). The idea for this class was to have the students act out the motion of the planets (in groups of four) so that they could directly see how the heliocentric model explains this phenomenon. I assumed it would be obvious to all the students that the geocentric model couldn’t easily explain retrograde motion, and for the most part I still feel this assumption was okay.

The main problem with the activity was that I simply did not spend enough time troubleshooting the writeup. I used way too much text to describe the activity and had no pictures. Some of the descriptions were vague as well. It seemed that most groups gave up trying to understand the activity fairly quickly, and called for my help instead of rereading. I point this out not to criticize them, but as something to keep in mind in the future when planning this sort of activity. Initially, I tried to help groups one at a time, hoping that some would get it on their own and that once I explained it to a group, more questions wouldn’t arise for a while. After getting through three groups it was clear that this strategy was a losing one. At the teacher's suggestion, I gathered the whole class in one spot, picked a few volunteers, and walked everybody through the activity together. This worked fairly well, but I think many got bored and/or weren’t paying attention. After asking for questions, all returned to their groups to try a second time. Most groups got it this time, with a little more encouragement. We went inside and spent the remaining time, about 15 minutes, discussing what happened. I wrote some discussion questions on the board for the students to copy down, but did not have a lot of time to take questions or clarify.

A few changes would make this activity go much smoother. Mostly, rewriting the assignment for clarity, and adding pictures. Better terms should be used for describing positioning and the directions to face. More emphasis on walking around the person acting as the sun, keeping the distance the same by using the rope. Smaller steps should be used so that data points are not so spread out. More thought should be put into the discussion questions, perhaps. Given more time the groups should act out the geocentric model as well so that they can compare the two systems. In the end the activity required twice as much time as planned for. Next time I will start with the demonstration!