Post-practice reflection

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Brief statement of principle

Post-practice reflection involves activities that follow successful completion of a quantitative problem aimed at helping students to understand the concepts associated with that problem and to develop abstract problem-solving schema. Such schema are a kind of knowledge component that if acquired with high feature validity will help students with solving similar (near transfer) problems, and perhaps also far-transfer problems.

Post-practice reflection activities often involve some kind of dialogue between the student and another agent (teacher, peer, or computer tutor).


Here is a sample Reflective Dialogue, incorporated within the Andes physics tutoring system (VanLehn et al., 2005):

An example of a Post-Practice Reflective Dialogue

ANDES PROBLEM ROTS4A: A 5.00 kg ball is attached to a 2.00 m rope which will break if the tension exceeds 100 N. If the ball is made to swing in a vertical circle, what is the maximum velocity with which the ball can pass through the lowest point?

    TUTOR: Which major principle did you need to solve the problem? [Just the name, please]

    STUDENT: Newton's 2nd law

    TUTOR: Yes. The main difference between this problem and most of the previous N2L problems is the fact that the direction of acceleration is __________. (fill in the blank)

    STUDENT: centripetal

    TUTOR: Correct. All else being the same, how would the velocity at the lowest point of the swing change if the length of the rope were doubled to 4.0 m?

    STUDENT: it would also double

    TUTOR: Well, it would increase, but it would not double; recall that the formula for centripetal acceleration involves the square of the velocity. If the radius doubles, the square of the velocity would double also, to maintain the same centripetal acceleration.

    All else being the same, how would the velocity at the lowest point of the swing change if the mass of the ball were doubled to 10 kg?

    STUDENT: it would decrease