Week 3

January 28, 2011

NOTE: this was written on September 11-ish of ’10. I wasn’t finished with it at the time, but I never did get back to it. See: 3rd sentence, re: nausea.

Three weeks in. Three lectures; as many labs. The abject panic has mostly subsided, the nausea has not. I wanted to have labs and lectures pretty well set before school started. For various reasons (ranging from beautiful summer days at the lake to funerals), that just didn’t happen. So, instead, I’m scrambling to get things done in time. Although this is the way I usually do thing, it is not the way I like to do them.

We’re still on Chapter 1 — mostly Kinematics. Is that where we should be starting? Heck, I don’t know. It’s simultaneously familiar and confusing, with the words we already know but now define slightly differently (what? you mean acceleration isn’t just speeding up?!? I can be slowing down and still accelerating???? …my family still brings up on occasion a particular Thanksgiving dinner, at which this was a primary conversational focal point. It’s almost at the “land-use/urban-planning argument” status in familial lore. I’ll save that fascinating story for another blog post.). In any case, the book starts with kinematics, so that’s where I start. At least for this semester. A rather difficult part of deciding to embark on SBG and inquiry methods is allowing myself to not be stellar this first go-round. No, my standards are not quite what I want them to be — but I think they’re better than what I used to have. No, I don’t test out my brand new labs on real students *before* I give them to my *actual* students — and sometimes it doesn’t work out quite so well. As of now we’re essentially following the layout of the book — maybe in a semester or two we’ll start with really important things, like Energy, and leave the kinematics for later.

Circles and Data

September 3, 2010

So, as part of this whole Inquiry thing, I’ll be asking my students to do some data analysis. Nothing that ought to be too challenging, but some manipulations they may have never been asked to do. In the spirit of “education” and all that, I thought it might be prudent to actually teach them the methods I expect them to use. Revolutionary, right? I know…I think I might be on to something here 🙂

[As an aside, last week I had a student walk out of a different class because he “[doesn’t] like to have [his] time wasted” with the “tedious bullshit” of having to learn the software he’ll be using to take data for the rest of the semester. Students. Sheesh.]

We started with something I assumed everyone was already familiar with: circles. In groups of 4-6 the students measured the diameter and circumference of 7 circles. I showed them how to find the averages and manipulate data in Excel, and as a class we made a chart of Circumference vs. Radius. Unsurprisingly, we had a nice straight line! I explained how this means we have a proportional relationship between our variables, and we can begin to write the equation: C ∝ r. Now this is a good start, but we’d like to do better….insert a trendline, find the slope, no big surprises: it’s π! We can now write a real equation: C = πr. Ta Da!!!!

So that’s all well and good, but not all of our relationships are going to be linear… what do we do when our initial graph isn’t a straight line? Try squaring things. For our forced example, Area would be the next logical step. Unfortunately, we were running out of time to have the class measure the areas of the circles, so I fudged some data. I showed them a graph of A vs. r (hey! that line’s curvy!!!) and A vs. r2 (hey! that line’s straight!!!! Now we know that A ∝ r2!). Again with the trendline, and Ta Da!!!! A = π r2

So how’d it all turn out? I think it went OK. I have some figuring-out to do with the data-sharing problem. Google Docs doesn’t have a trendline function (not an easy one, anyway), and I can’t seem to set the correct permissions on our college’s shared Student drive to allow them to save changes to an Excel file. Irritating. I didn’t leave enough time to complete all the activities, and they were definitely antsy by the end. I had to remind them that class is not over until 8:50, so would they please sit back down at 8:45 and listen for the next five minutes? It was a reasonable introduction to Excel, I think, but overall it was less the student-directed activity I wanted it to be, and after the introductory measuring it felt primarily like a lecture in which they were following along on their own laptops instead of taking notes. If I do this again next year, I would allot at least two hours for the activity, and give them a cheat-sheet of Excel commands so that they could work more on their own, and I could circle through the class to help as needed.

But no one, as far as I could tell, left the room muttering “tedious bullshit” under their breath. That’s a win, right?