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.

MFE - Starting Lesson 1

Welcome to my reflections on teaching the Motion, Force and Energy unit. I asked Karen if I could teach one period a day to get an understanding of what this unit looks like (and feels like) to teach in a real 8th grade classroom.

We got the carts and tracks to work using the appropriate motion by with 500 g on the plunger cart and pushing the plunger in to the "2". For the fan cart, we put in three batteries and replaced the 4th with the aluminum cylinder.

Today we started with Lesson 1. I probably spent a little too much time showing kids the carts on the tracks. I thought they were going to get more excited about it - maybe it's just first period, maybe it's May, or maybe it's just that they weren't the ones handling the materials.

Students were able to describe that the plunger cart was traveling at constant speed and the fan cart was speeding up when I asked them to describe the motion in the large group; but later on in their smaller group discussions and on the representations on the whiteboards, they referred to the plunger cart as speeding up and slowing down.

Students were looking at the launch as speeding up and the "catcher" as slowing it down; so we had to redirect them to look after the launch and before the slowdown.

In order to get each student to respond when they thought the carts were traveling at the same speed, I asked them to raise their hands when they thought the carts were traveling the same speed. About half the class (maybe more) thought that the carts were traveling the same speed when they were at the same position on the track and another group thought the carts were traveling the same speed at a time when the fan cart was behind the plunger cart.

Students spent about 15 minutes writing their groups' ideas on the whiteboard, I hurried them along from their own representations (most had 2 or 3 representations before sharing) because I spent too much time on the introduction. I was glad to have several sets of whiteboards so they could return to them tomorrow.

I saw lots of graphs, tables, and a variety of pictures that represented the motions. One weakness I saw and will address tomorrow is how students use their representations to support the idea that there is a certain time or position where the two carts are traveling the same speed.