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.

Time and Elicitation - frustration

Yikes, elicitation lessons take time! It has been so tempting to pre-teach, draw students attention to something that they're going to learn, etc, in the elicitation and really delve deeply into student ideas. Tomorrow we'll power through the last couple of presentations so we can jump into Lesson 2. My goal for the next elicitation lesson will be two days (no longer) and perhaps I can ask my questions to groups as I am going around looking at their work.

Today, being a Weds, students worked on their boards for another 12 minutes before half the class presented. They did focus more on where and when the cars were at when they were traveling the same speed. Same two ideas are coming out - either the plunger car (blue car, in our case) was ahead of the fan car (red car) when they were traveling the same speed, or the two cars were at the same location when they were traveling the same speed. Sometimes these competing ideas were on the same board.

Another interesting observation: most groups that presented today are convinced that the plunger car slows down throughout it's path. Their explanations for this are gravity and friction. Makes sense based on their experiences, but not what they see in the lab. We made sure that our demonstration cart didn't visibly slow down throughout the trial. I tried to not pursue this one too heartily since those ideas will be further developed later in the unit. I did try to focus on the movement they could actually see (after the cart was launched and before it was stopped). I will try to not focus on this (the changing speed of the plunger cart) tomorrow, they'll have experiences with it soon enough.