This document discusses strategies for helping students construct mathematical arguments and critique the reasoning of others. It introduces the idea of having students determine whether mathematical statements are always, sometimes, or never true and provide arguments to support their categorization. Video examples show students attempting to prove statements about addition and the equal sign. The document suggests moves like examples, counterexamples, and describing concepts without numbers that help build convincing arguments. It encourages teachers to have students practice these argument skills and reflects on how the strategies support mathematical standards and practices.