"One strategy […] that we use to help students develop precision and rigor in their writing is the incorrect proof assignment."
We model precision and rigor in mathematical writing right from the start. One strategy, in particular, that we use to help students develop precision and rigor in their writing is the incorrect proof assignment. This assignment involves a brief probability proof, in which probabilities are multiplied because independence is assumed without that assumption being explicitly stated. That assumption is incorrect. So the mathematical purpose of the assignment is increase students’ awareness of the importance of independence when multiplying probabilities, while the communication purpose is to illustrate the importance of explaining assumptions in sufficient detail to ensure that proofs are rigorous. Students revise the proof to practice this skill.
