Thursday, March 24, 2011

On the Perils of Pushing for Correctness

Last semester, I gave intro physics students a series of easy, commonsense questions about force and motion. Before instruction, students were doing between 80% and 95% correct on the questions. After instruction, students were doing fairly bad, between 25 and 50% correct. It seemed from the data that students had learned to ignore their productive intuitions, and were simply trying to apply rules that made no sense to them. While we may have eradicated their misconceptions (they no longer say a truck exerts more force on a car than vice versa), we eradicated any sensibility toward the world as well.

It reminded me of an excerpt described below:

Eleanor Duckworth (1996) describes an experiment in which children were taught about density as an explanation for sinking and floating (in a "cognitive acceleration" experiment):

"Among the rules Englemann taught the children, the principle on was : 'An object floats because it is lighter than a piece of water the same size; An objects sinks because it is heavier than a piece of water the same size. Kamii and Derman describe fascinating instances of conflicts between the rules children were taught and their own intuitions–their common sense." In addition to the rules they often gave other explanations, typical of school children their age: 'because it's heavy', 'because it's little', 'because it has cracks in it', 'because I pushed it'; or simply, 'I don't know why.'

"In other instances, the rules seemed to come between the children and their intuitions in ways that led to nonsense not normally encountered in children their age. One child hefted a large candle in one hand and a birthday candle in the other, but having seen that the both floated, maintained, 'they weigh the same.' Another child said that a tiny piece of aluminum that sank weighed more than a large sheet that floated on the surface. Clearly these children were trying to apply rules rather than coming to terms with objects. A typical 6-year-old's reaction to the aluminum foil, for example, might be to say that the tiny piece sank because it was too tiny, and the large piece floated because it was flat.

"In another part of the Kamii and Derman assessment, no longer dealing with sinking and floating, the children were asked why the water level rose in a glass when an object was immersed in it. Two of the four replied, 'Because it is heavier than a piece of water the same size.' The other two children, who tended generally to remain true to their intuitions, answered that the object pushed the water out of the way."
Duckworth (1996) On the Having of Wonderful Ideas.

Englemann (1971). Does the Piagetian approach imply instruction? In Green, Ford, & Flamer (Eds.) Measurement and Piaget. New York: Macgraw Hill

Kamii and Derman (1971) Comments in Englemann's paper. In Green, Ford, & Flamer (Eds.) Measurement and Piaget. New York: Macgraw Hill

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