Lesson 4

THERE IS AN ERROR IN THE WORKBOOK! It says to open 4B (second progam) but that is for the acceleration lesson!

I set up the tracks and you can have the motion detectors set up at at the 5 cm mark and the carts start at 30 cm for the NEW motion detectors. This gives the students more track to work with. Helps...especially with the fans turned on. The old ones work better at 50 cm.

I made a few changes to the workbook and had the students change their copies. If you want to see my changes, email me and I'll send it to you.

I introduced the lesson after finishing lesson 3.3 today. We will start it first thing Monday. I have 4 tracks on counters and 4 on tables (that are pushed together). Wish me luck!

Lesson 3

3.1 and 3.2 worked most smoothly with 2 kids to a computer, if you have access to additional laptops. I added a box for explaining predictions above the graph in #7 and 10. I also asked students to get into the habit of labeling the axes of graphs like the computer printouts, both to make sure that they were differentiating between speed-time/position-time and because when I was working through #13 I found it much easier to have some units. Some kids had rationalizations like "The position graph is steeper when it is faster because it is going farther in a certain about of time." I asked all groups to show me their work when they got an initial idea for #13; I found many students misinterpreted this (because the actual question is above the graphs, not just where it actually says #13.), and just described the graphs instead of actually coming up with a rule that they could apply. They were able to do this well in the end, but it took a few check-ins. Rise over run came up frequently. I usually told students that was excellent, but also encouraged them to think about what rise would signify (what does it represent if it goes higher on the y-axis?).

I wonder if we could have a more clear-cut graph for #14 - I didn't see it causing problems with students, but when I did it it looks like it goes 100 m in 2 sec, or 50 m/s, while according to the data it is technically 40 m/s. This makes sense, because it just means my reading of the graph was off by 1/2 of a second, but it seems like if this is their first opportunity to check their strategy kids could think they've done it incorrectly. Probably not though - I haven't had that question come up yet.

Review/Debrief after 3.2

I decided to do a debrief/review after 3.2 to make sure everyone was understanding the concepts. I created a SmartBoard file to help. Let me know if you want a copy of it via email.

Watch for this in Lesson 2

Today at the end of Lesson 2, I started seeing that students' interpretations of the position-time graphs (and also their copying of the graphs from the Logger Pro application) was incomplete.

There were two ways they graphed these two graphs - I've drawn them crudely below:

The top graph is often interpreted by students as the red line is the faster motion and the black line is the slower motion rather than that they are both approximately traveling at the same constant speed. About half the class had a graph that looked like the top graph.

We agreed that the flat spots on the position-time graphs represented no motion, so then we just compared the first part of the motion for each of the two graphs that students reported.

I had a student collect and "store latest run" up in front of the class (projected on the SmartBoard) so that we could show the class the motion on the same graph. I then had students talk with their table group about which of the two graphs to the left best matched the data we collected up front. There was agreeement that the graph that best matched the motion up front was the second graph. Students were then instructed to make sure their understanding was written in their idea journal.

Also, watch for students who want to start these graphs at 0,0. That's not what the computer shows.

Lesson 3.1

This lesson goes very fast. Definitely can do it in one period. I handed back a bunch of papers and almost everyone still got through the entire lesson. I just have a few students that need to finish up the table tomorrow.

Lesson 2

This lesson went pretty well. I let the kids work on their own and it took two days. I had to help them with the graphs, though. They didn't understand that they had the position/time on the top one and the speed/time on the bottom one. They also didn't understand that they should have three lines on each graph.

I had colored pencils available for them for the graphs. It made it much easier.

I went around to each table for "check off" and discussed question #12. It seemed that each table understood the graphs, but could do better describing the lines in terms of "slope." Some groups that got confused, we discussed what a graph would look like if had a car going down the highway if we were going at a constant speed. That seemed to help, especially with the speed graph.

The shortcut CTRL+L didn't seem to work for some computers (?) but you could still use the drop down menu to save the latest run. FYI.

Elicitation Temptations

Ahhh, finally I resisted temptation during the elicitation presentations. Listening to student ideas and seeing what students have on their whiteboards and only asking questions without commentary is sooooo challenging!

Yesterday I succumbed to temptation and highlighted conflicts between what was said and written, and between two different representations of motion that came to different conclusions rather than making mental or physical notes to look for those conflicts after students have had lesson experiences on which they can build this understanding.

It's hard not to "teach" in the elicitation lessons, but to take on the role of listener and summarizer of the ideas that are presented. I also found that elicitation went more quickly when I didn't interject. In retrospect, I think this elicitation lesson can be done in two days.

At the end of the lesson, we summarized the two ideas about the position of the carts when they were traveling the same speed and summarized the variety of ways students expressed motion. This provided a bridge to the data collection tools we'll use tomorrow to gather motion data.

Most of the representations were only concerned with speed and very few explained this in terms of changing position and time. I think this will be something to watch for - since students calculated speed so much last year in last year's unit, there might not be conceptual grounding for an understanding of speed as something outside of a mathematical understanding. What I mean is that speed represents a change in position during a particular interval of time not just "distance divided by time". The latter will cause some confusion when there is changing direction (Part 2) or several intervals of time to consider.