Eliciting student ideas with little toy cars (Blogging from the AAPT)

by Stephanie Chasteen on July 26, 2009

Today’s session is all about using diagnosis, or assessment, in your teaching (“Designing a Diagnostic Learning Environment in the Pre-College Classroom”; Lezlie DeWater, Eleanor Close, and Hunter Close).

In the last post I talked about one way to elicit students ideas, using a video and brainstorm.  This time, they gave us a bunch of pull-back cars to play with — cars that you pull backwards (storing up some energy) and then move forward when you let them go.  It’s amazing how easy it is to get physics teachers to play around!  You could use a pull back car from Arbor Scientific (below), or create a different kind of activity with remote control cars like those at the Xenon Project.

Then we went, as groups, to flip-chart paper, and were asked to “make a representation of what you notice about the car and how it moves.”  We spent a while doing that, drawing arrows and pictures and words, and instructor circulated asking questions like “what does that line mean?” or “why is there a smiley face there?”  We then did a “gallery walk” to see what other groups had drawn.

  • Many people noticed that a small backwards pull gave the car a lot of forward motion, and some people tried to measure how far forward it would move for a certain amount of pull-back.
  • Some noted that there were different kinds of energy (eg., KE, U, and work) and gave some some of pie chart or graph showing the different amounts.
  • Some showed the motion of the cars going straight or curved
  • Some pictures were more artistic and had pictures, some had graphs or data, some drew vectors and representations of the motion.

How does this help students and instuctors?

  • It gives students feedback, as the instructors asked them questions about what they’d drawn
  • It gives students feedback, as they see what others have drawn and how it’s similar or different from what they drew
  • It reinforces your ideas to see other students notice the same thing you did
  • It gives students a broader view of the phenomenon to see what other students drew that they didn’t key into
  • As an instructor, you can listen to how students are explaining their drawings to each other during the gallery walk and get an idea of what they’re thinking.

One concern is — will students think that it’s a contest to get the “better” poster, and try to figure out which poster is the best?  Students have a lot of ego competitiveness.

Some strategies to avoid this kind of thinking is to set this up as “what are some of the things you liked in different posters?”  Or, highlight the “smart” elements that are present in the poster that they might see as the “idiot” poster.  Students and teachers can have different ideas about what constitutes “science-like” representations — this is a chance to try to make your ideas about “what is science” explicit.

How does this fit into a broader framework of “how we teach?”  We were given a handout about the Algebra Project (see “Radical Equations” by Robert Moses, 2000, p. 120).

1.  Students start with a physical event — a trip or some other event.  For us, we played with cars.  Another example is taking a trip on the metro.

2.  Student gives a pictorial representation, giving an abstract representation of that event.  For us, it was writing on posters about the cars and giving some sort of picture.  For the metro trip, it could be making a picture of that trip.

3.  Students use “people talk” to discuss pictures. When we discussed the posters in general casual language, we told our stories of our drawings in “normal” language.  This gives teachers and students a window into student ideas.

4.  Students move towards more structured language. The event is translated into more physics talk, using words like start, finish, energy, direction, distance.  We get students to develop physics or math models for important features of the event.  This is a particularly deliberate process in the class.  In this activity, for example, we could identify “giver of energy,” “receiver of energy,” forms of energy,” “evidence for energy.”  The class then made new representations showing these different aspects of the car over time.

5.  Symbolic representation. After the first four steps have happened, then students can start to make some sort of symbolic representation that makes sense to them.  These are personal representations, but then students move towards some representation that everyone can understand, so everyone in the class can communicate.

This process helps students make sense of abstract symbols that, too often for students, are devoid of meaning.  A game that they are unable to play.  Students create their own mathematical and physical truths through their own direct experience.


On a side note — they’ve developed a very nice online tool called Diagnoser which lets you assign question sets to students, and their answers give information to teachers about just what difficulties students are struggling with.  For example, if they look at a graph and give a particular answer for the speed at a point, they may be confusing position and speed.  Diagnoser will give you summary information for your class (as well as for each student) about common difficulties in your class. There are also several elicitation activities included in the site and example lessons for addressing these difficulties.


Early Learning Toys December 3, 2009 at 6:18 pm

A well researched site, I’ll link to it from my site thanks

Nerf Stampede February 4, 2011 at 3:45 am

great tips..thank you 🙂

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