Isaac’s Wheels – Background


This episode is from Responsive Teaching in Science, an NSF-funded project focused on cultivating instructional practices of attending and responding to student thinking.

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Sharon Fargason’s third-grade class, at an urban west-coast public elementary school were studying motion. Their work had begun several weeks earlier, when Sharon had shown them a toy car and asked what could get it moving. Students had lots of ideas, about rubber bands and ramps, pushing and blowing, even rocket boosters and jet packs.These provoked new questions and things to do, from fantasizing about a roller coaster to debating what would make the car (or other object) go faster. These activities made up the class’s science activities for 16 days, spread over six weeks starting in mid-September.

We studied a moment that took place on the 14th day. In the days immediately preceding, the students had been experimenting and debating over whether the weight of an object affects its speed sliding down a ramp.

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Sharon opened the discussion by asking Jamir to describe his observation from the day before: He had placed a rubber doorstop on a fairly steep ramp, expecting it to slide, but he found it stayed put. When he went to show the class, the doorstop slid. That inspired conversation about what affects when and how the doorstop would slide.

Several students gave reasons to support ideas that it’s the object’s shape (round or not), the material (rubbery things stick rather than slide), or the angle of the ramp that determines the doorstop’s motion.

About 30 minutes into the discussion, Isaac, who has not yet spoken that day, raised his hand to say “it matters…if it has wheels.” Sharon remembered seeing something interesting in his notebook about wheels, and she invited him to tell the class about it.

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