We began with a students-talking task, in which common student ideas were likely to come up, and asked students to comment on these. 

We modified the question to be open ended; this way physics educators could focus on one student-reasoning response at a time. (See image at left.)

Acceleration requires a net force; if the bucket is moving but not accelerating, then the forces must be balanced. We anticipate that this question will elicit responses related to the common idea that motion requires a net force; or that the balanced forces are a consequence of Newton's 3rd Law.