To be honest, it's leading (or guiding) the discussions that worries me the most. I know I'll get better at it but that feels like the shakiest ground right now. Maybe I should look for a "unlocking your inner Socrates" self-help book. :-)
So here's the video of lab # 1, where we tried to figure out if a toy car actually moved at a constant speed. (Don took this video & posted it on Vine -- Thanks, Don!)
https://vine.co/v/eiMtMnvdF3L
The intro to this lab was "hey, look at this toy car, what do you observe?", making a big list of all the facts, & then crossing out everything but "constant speed". We had a few minutes to discuss in our groups how we'd figure out the speed, then we reported out. Don said one way was too easy (measuring how long it took for the car to travel a meter) so all the groups had to do it the hard way, marking out how far the car traveled in x number of seconds. (We chose 2 seconds -- Trying to do a mark a second was a bit much.)
Once we had that done (& we did 3 trials, because human error is a big issue in this lab -- saying the seconds on time, marking the distance traveled on time, those are hard to get right), we got part 2 of the lab. We had to turn our car around on our starting line & go 10 seconds in the opposite direction. (Every group had a different part 2: Start from the end point & go back, try it with a blue car, start at 1 meter, etc.)
& then of course we made a whiteboard:
There was a big discussion & Don asked why some slopes were negative, why we said "position" instead of "distance", & what were the "for every" for the slopes. (The blue cars were half-powered & went painfully slow. I'm kind of glad we didn't have one.) This discussion uncovered the difference between speed & velocity, so then of course we graphed the velocity for both our experiments:
More discussion, especially about how negative slopes on the distance-vs-time graphs become lines below the horizontal axis on the velocity-vs-time graphs. & also just good discussion about the nature of both types of graphs -- What do they really show? One group presented a great critical competitor:
This graph got us into the difference between graphing speed vs graphing velocity. They fixed their graph (the labels) to be accurate. This will be a trick with moody teenagers -- discussing things so that classmates see their errors & fix them rather than snarking at people for being obtuse. I sure hope I've got a good group of kids to practice discussions with next year!
& then it was time to go home, do a worksheet, read a section of the Arons book (http://www.amazon.com/Teaching-Introductory-Physics-Arnold-Arons/dp/0471137073), & blog/ tweet as appropriate.
We started the next day off with a discussion of the Arons section, which was the intro to why he wrote the book -- how students don't really understand the concepts (what really is area, what really is a ratio), they're not asked to explain their reasoning so instead they've only got shallow algorithmic understanding, etc etc. (Sorry, I forgot to snap a picture of our whiteboard with likes, dislikes, & questions.) He was writing in the '90s citing data from the '70s ... & it's now 20 (or 40!) years later & these issues are still problems. I need to take better discussion notes, altho really this is all stuff we discussed in my Woodrow Wilson Teaching Fellowship classes. [Side note; I wish we got the hardcover edition of this book, like Don & Laura both have -- It'd be easier to handle.]
& back into the physics! We pulled out our whiteboards from the buggy labs & figured out that the area under the curve (more accurately, the area between our line & the horizontal axis) on the velocity-vs-time graph was the displacement of the buggy (as opposed to the distance traveled by the buggy). Then we built "the model so far" on the front board. I really need to take much better discussion notes -- what are the transitions like, what sorts of questions do Don & Laura ask, how do they lead us to realize contradictions & weaknesses in our thinking? Of course, that's hard to do while I'm also taking notes on the actual physics...
The worksheets so far (& I expect forever) tie directly into what we've just done & help to solidify concepts. They're a bit vague & Don was noting the poor graphics. Worksheets can either be homework or in-class assignments but so far they've all gotten whiteboarded. (Is that really a verb? O well, it is now.) Even tho we work on the problems by ourselves, we put them on a board as a group. Not every question, & sometimes groups write up the same questions as other groups, but everything gets discussed. Here's the whiteboard we did:
Up to this point, things have been pretty basic. I mean, it's only Unit 2, how complicated can it have gotten. Well, now we introduce motion maps. I'll have to figure out a different way to do this because the fake-strobe gave me a terrible headache.
After the strobe-motion demonstration, Don led a discussion about how to record what we saw & voila, he came up with the dots-&-arrows of the motion map. We talked about them some, wrote out dots for the fast buggy & the slow buggy, & then had a reading from Unit 2. This is the only content reading we've done so far, & it was just a couple pages about motion maps & some examples. No, seriously. All the other content we've learned has been thru experimentation & discussion. & then we had a worksheet, which we whiteboarded & discussed, & then we wrapped up the unit with a challenge activity.
So, for the t-bone challenge, we took the 2 buggies & tried to make them collide on an X. There's 2 start lines, both 2 meters away & orthogonal to each other (I love that word! It just means at a right angle). We couldn't test it out beforehand but we could figure out the speed for the buggies & make predictions, etc. Here's all the instruction Don gave us (note the motion dots at the top of the discussion board):
So yes, vague enough to get started. We calculated velocities, figured out displacement (via the area method), & whiteboarded that:
If we released both buggies at the same time, the fast buggy would've had to start 5 meters back from the X, which we figured just asked for a curvature error. So we released them both at the 2 meter starting lines, only we released the fast buggy about 7 seconds after the slow buggy. We only had one chance at this & sadly our buggies failed to collide. (Our releaser was off by a second. The 2nd time worked perfectly, when it didn't count.) So here's our video:
After all that excitement, it was time to go home. The readings over the weekend were kind of more of the same. We read another bit of the Arons book, which focused on how teachers ought to lead students to explicitly state their thinking (because otherwise students won't crystallize their ideas & teachers can't see hidden misconceptions). Seriously, there was a lot of "leading students" -- I don't think that's the right terminology. "Guiding students" would be better, since it implies that the students are discovering the knowledge on their own. (You can lead a student to physics but you can't make them think. Ha ha! [OK, I know, I'm not that funny...] ) & the Wells method paper answered a bunch of questions from the first reading. It's very sad that he died of Lou Gehrig's disease. But the original modeling protocol is, like, 20-some years old. I'm sure it's changed since this paper was written. Heck, it's changed since the worksheets in our binder were created (in 2006). So these both are more historical background & perennial suggestions more than immediately helpful.
Here is the whiteboard for the Arons, from our discussion Monday morning:
So, 2 units (& 3 days) in... I'm really happy to be refreshing my physics. (I'd like to refresh my calculus too but that can wait.) The modeling stuff we're learning goes hand-in-hand with what my WWTF professors stressed ... only this is an actual demonstration, not just "you should do this, it works". I don't know how much of the equipment we have. It'll cost ~$100 for a 5-group set of buggies (that includes shipping & batteries, the buggies themselves are like $8 each) & the LoggerPro software is only $250 for the whole school ... but this is only Unit 2 & I know there's essential equipment coming up in Unit 3 that's darned pricey. I really wish I'd had this workshop before I had to turn in my "shopping list" in June. I'm just going to have to go spend some time in the science storage area, which unfortunately is not attached to my room. (But I shouldn't complain, I've got the biggest science room in the building.)
This is a great experience. I'm trying to figure out how to do this for biology, but maybe I just ought to concentrate on the physics for the next few weeks.
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