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Stage 0:  Lots of lecture – not much else to say about that.

Stage 1:

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Stage 2:  Start with the question:  Which is more difficult – pulling a truck or pulling a lineman across astroturf?  Students will immediately have opinions one way or another.  (Usually they think that pulling a truck is harder because it’s “heavier”.)

I split the students into group and have each group agree on which object will be more difficult to pull and guess how much force each will require.  (This is my favorite part of the lesson – so often students have no concept of how much force a Newton is.  If they ask for some guidance, I inform them that I weigh about 500 N.  Students find this shocking.  They think 500 N is a HUGE amount of force.) 

Once each group has their guesses solidified, we then watch this video and the students work to explain why a flea was able to pull something so heavy (no friction!):


I have the students make a list of factors they think might affect an object’s friction and have them test them out (different weights, different surfaces, etc.)  This leads us nicely into coefficients of friction and other discussions.

Usually at this point, students are still convinced the truck will require more force – after all, pretty much all of our tests confirmed that heavier objects ARE more difficult to pull.  We try it out (I let them each try to pull my car using an ENORMOUS force sensor that one of the math classes built last year).  They then try pulling each other across astroturf – most of the students were not strong enough to pull ANY of their classmates across the turf.

(These are the lessons that I have actually given in my 3 years of teaching AP Physics.)

Stage 0:  So, Torque is force multiplied by the distance to the pivot point.  You must use the component of the force that is perpendicular to the distance.  Torque makes things rotate.  Awesome, huh?

Stage 1:  Torque lab stations:  

Stage 2:  We started class by watching this video:

The obvious question is "holy crap, how did that happen?"  which provided a nice segue from our study of fluid mechanics (which we are just finishing) into torque. 
We started by listing factor that might affect whether or not a truck would get knocked over by wind.  We then analyzed the fluid mechanics behind it and began our analysis of the actual tipping.
(I have to admit I am a little embarrassed that stage 0 and stage 1 are real lessons that at one point I thought were pretty awesome.

I am trying out a new technique for test and exam review this year with my AP Physics students.  They all have a year of honors physics behind them, so reviewing concepts is mostly a waste of time.  They know the material pretty well, and right now are just struggling with fitting it all together.  (Knowing when they can and cannot use COE, how to break down a complex problem into smaller parts, etc.)  I have had a lot of requests from students to just tell them the steps they will need to go through to solve some of the problems.  And while that sounds like a lot of fun (ahem) I am not convinced it will be worthwhile.  I want them to get used to working through problems that they have never seen before and to learn how to use their understanding instead of a scripted procedure to solve problems.

So I am trying two different techniques for test “reviews”.

First, goal-less problems.  They are awesome.  And sooo easy to create.  Just take an AP problem (or any problem for that matter) and remove the question.  Then we can discuss what we can(or cannot)  solve for and how to solve for each unknown.  (There are usually lots and lots of possibilities.)

Second, (and this is what I am doing this week) I want them to solve “real” problems.  So I will find a video on youtube, an video of Angry Birds, etc. and have them analyze the physics.  (This is again similar to a goal-less problem, but a little more fun.)  On Monday, we will be looking at a video of the blue Angry Birds (the ones that split into 3 birds in the air) to figure out what exactly is happening.  Is momentum conserved?  Energy?  Why?  Are they on Earth?  In order to speed up the process I went ahead and loaded the video into Tracker and printed out the x and y position and velocity graphs.  Yes, I realize that ideally they could do this themselves, but for the purpose of a test review I want to spend the time actually looking at the physics instead of learning how to use the software.  It should still be a challenge for them to figure out what parts of the graphs are relevant and how to use them for momentum and energy problems (this is not something we have specifically done yet.)  Hopefully practicing with a fairly open-ended and less structured problem will make them more comfortable when they see an unfamiliar problem that lists all of the information they need and tells them specifically what questions they need to answer.

This is my third year teaching AP Physics.  I have the benefit of being able to teach a group of students who have already completed (successfully) a year of honors physics (which I also taught).  This is fabulous, except for the fact that they already know pretty much all of the content they need.  In the past, no matter how interesting I tried to make the class, it still felt like I was just re-teaching them stuff they already knew (which I was) and they were bored (for valid reasons).  This year, I completely changed things around.

The first week or so of class I spent going over some details that we had kind of breezed over last year (when to rotate coordinate systems, further analysis of the difference between static and kinetic friction, etc.).  We then spent one day reviewing the “models” that we had developed last year – ie, constant velocity, constant acceleration, projectiles, COE, COM, central force, etc and reviewed when each was and was not valid.  (During this time, the students were also working through some AP problems for homework.)

Now that they have their heads back in the game and refreshed their memories, we have the rest of the trimester (until about Thanksgiving) to do some real physics.  Stuff that they are interested in and that requires a little more thinking than just trudging through problem after problem (or watching me trudge through problem after problem).  I realized (not surprisingly) that there are about a million youtube videos out there that are AP problems in disguise!  Except they’re even better, because they require the students to decide what information they need (instead of having it listed for them at the top of the page).  Awesome.  (Plus, the students think they’re pretty cool.  That never hurts anything.)

Today, we started our first project.  I showed them this video:

Without any prompting, the kids immediately asked “is that real?”  Well, I have no idea.  Why don’t we find out?  (Actually, I do have a pretty good idea.  But I wasn’t about to tell them that.)  The class was split between students who were convinced it was fabricated and those who really, really wanted it to be real.

Since this was their first problem of this kind we came up (as a class) with a list of information that they would need to collect in order to solve the problem.  (I let them come up with the list and simply wrote their suggestions on the board.  I really, really wanted to jump in a few times to point out why some of these pieces were irrelevant, but I refrained.  Remember how I’m trying to be less helpful?  Yeah, that’s hard sometimes.  But worth it.  As it turns out, once they started working the problem most of them figured out what info was irrelevant and what stuff mattered.)  The students spent the rest of class looking up distances and determining whether or not this could reasonably be a real shot or if it was faked.  Tomorrow we are going down to the gym and using my Flip camera to collect videos of them attempting half-court shots.  (And let me tell you, they are pretty darn excited about that.)  That way we can compare the analysis of a real shot to the youtube video.

Next project:  car crash anaysis, maybe?

I have two main goals for myself this year (both of which are way harder than I would have thought):

  1. Really listen to my kids.  Don’t correct them, but pay attention to what they’re saying and try to figure out where their misconceptions are.
  2. Be less helpful.  I have talked repeatedly about how it’s okay to make mistakes as long as we learn from them.  It’s impossible to learn from mistakes if your teacher jumps in and fixes them before you can make any.
For the past couple of days in my 9th grade physics class, we have been discussing motion maps and position-time graphs (along with the buggy lab).  I introduced motion maps by talking about what you can tell about a person’s motion just by the footprints they leave behind.  For the most part, it made complete sense and posed no real problems for the students – until we started talking about what happens when that person stops.  How do you know they stopped?  Can you tell how long they were standing there?  I asked for some ideas on how we could represent (or model) someone standing still.  One student eagerly suggested that we “stretch it”. I have to admit made no sense to me.  My initial instinct was to give him the standard “oh, that’s an idea” response and keep asking until someone came up with what I wanted.  But I was intrigued by his comment and a little curious as to what the heck he was talking about.  So I asked a few questions, trying to get him to explain what he had meant.  After a little time (and probably a little frustration that we clearly were not understanding each other) he finally realized that he was confusing motion maps and position-time graphs and was under the impression that the axis represented time instead of position.  Aha!!!  “Stretching it” would make complete sense in that case!
Going into the Buggy Lab, I was planning on talking my students through how they might want to plot their graphs.  (In other words, I was planning on telling them what to do.)   At last minute, I decided to just let them plot what they wanted and see how it turned out.  Seeing how my students graph their data gives me a LOT of information about what they’re really thinking and I wanted to make sure that our first “board meeting” was more than just kids standing up an repeating what I had told them to do.  I really fought my impulses and let them create whiteboard with mistakes (gasp).  At one point I made myself sit in a chair at the front of the room and just watch so that I couldn’t jump in even if I had wanted to.  (This just happened to be the time that my principal decided to stop in to see what we were doing.  I had to fight the urge to jump up and start helping to prove to him that I really was doing my job and not just sitting there twiddling my thumbs.)  My hope is that tomorrow during our board meeting, we can explore why some graphs are more useful than others and why.

Before the start of the school year, I went back and forth on whether I wanted to do the Marshmallow Challenge the first day or just jump right into physics.  (That’s always fun.  It completely throws the kids for a loop when the first words they ever hear from me are entirely about physics concepts. )  I finally settled on the marshmallow challenge, mainly because my co-worker convinced me (exactly 1 week before school started) to try out SBG this year.

The kids really enjoyed the challenge, but my main purpose was two-fold:

  • I wanted them to start questioning their definitions of “smart”.  When they found out that kindergarten students performed much better in the challenge than MBA students, we had a nice discussion about what it means to be smart and how to succeed.
  • I wanted them to recognize that “high stakes” situations or incentives do not necessarily lead to better performance.  I asked the kids if they thought they would have done better if I had told them that the winner gets an automatic ‘A’ in the class.  They were initially split but after some discussion decided they may have actually done worse.  (There was some debate with sports analogies.  Some students argued that when their team plays a big rival they end up doing really well.  They soon modified that statement, though.  They do well when they have worked hard and are excited to show off how much they have improved by beating a team that usually beats them.  They end up flopping when they get nervous and overly anxious about the game.)
Overall, a good start to the class and I think this will be a good lead-in to our discussion about SBG.  (I was hoping to introduce SBG on the first day of class, since it is a huge change from what they are used to, but like I said, I made up my mind about SBG one week before school started.  I am still frantically trying to put the finishing touches on my list of standards and recommended practice problems.  I have a feeling it will be quite a bit of work, but totally worth it.)


This is my third year teaching AP Physics.  I have a group of students who have already completed and honors physics course during which they learned most of the information needed for AP.  Initially, I thought this would be fabulous (and it really is for the most part).  The problem is that I have had a difficult time figuring out how to keep the students interested and challenged when they are essentially (from their perspective) learning nothing new.

Then I discovered goal-less problems.  (Thanks, Kelly!)  For the first day of class, I turned Dan Meyer’s boat in the river video into a goal-less problem and told the kids to represent Dan’s motion going up the down escalator in as many ways as possible.  They should use mathematical models, graphs, charts, diagrams, and solve for any and all unknowns they can think of.  Initially, there was a lot of “Wait, where’s the rest of the video?” type questions.  After some initial confusion and hesitation (I’m pretty sure these kids are NOT used to such open-endedness) they got down to work.

Overall, I am thrilled with how it went.  For the first time, I feel like my AP class is going to be much more student-driven.  Walking around class, I was able to get a really good gauge of where the kids were and was pleasantly surprised by how much complexity there is underlying what seemed to me like fairly straight-forward (constant velocity) motion.  They got into breaking the motion down into x and y component, free-body diagrams, friction, Newton’s 3rd law, etc.  This will serve as a great starting-off point for further discussions.  My hope is to continue getting them used to applying all types of models to one scenario instead of segregating separate units.

I did forget to start the class by discussing what we can measure, what values we can calculate, etc.  They definitely could have benefited from that discussion – there was way too much time wasted trying to figure out what they could calculate and what they could measure and what exactly they were should do (“Do we need exact values on the graphs?  Do we have to calculate the speed of the escalator?”) For their first experience with goal-less problems a focused discussion about where they could take this could have gone a long way.

The only problem I ran into today was focus – some groups were great, stayed on task, and really thought about what they knew and how they could represent the motion in new ways.  Some groups, however, sketched some qualitative motion graphs and stopped there.  I spent a lot of time trying to re-direct them and get them to realize that they had NOT actually written down everything there possibly was to know about the motion.  I am not sure what to do about that.  Hopefully as the year progresses they’ll realize the benefit to themselves to really think through each problem thoroughly.