CCSS.Math.Practice.MP3
The Standard
Construct viable arguments and critique the reasoning of others.
Common Core State Standards for Mathematics
What This Standard Means
What Students Need to Do
Students make a mathematical claim and support it with objects, diagrams, examples, definitions, calculations, or known results. They examine another person’s reasoning, ask questions, identify gaps or counterexamples, and suggest corrections.
What Mastery Looks Like
Students connect each claim to a definition, model, calculation, or known result. They can find gaps or counterexamples in another argument, ask a useful question, and revise their own reasoning.
Common Misconceptions
Students may think several examples prove a claim for every case. They may focus only on the final answer, reject unfamiliar methods, or name an error without explaining why it fails.
How to Assess It
Display a solution from today’s lesson with one deliberate reasoning error. Ask students to identify the first flawed step, explain why it fails, and correct it.
Ways to Teach It
- Give pairs counters, tiles, or algebra cards to build two models, then use each model to defend the same mathematical claim.
- Have students write, “I agree or disagree because,” after reading a two-step solution, then cite the exact step supporting their view.
- Run an Error Hunt with solution cards, awarding points for finding the first flawed step and giving a valid correction.
- Use class survey data to test a claim about students, then discuss whether the sample supports the conclusion and what limits remain.
Related Standards
- CCSS.Math.Content.HSA-REI.A
Understand solving equations as a process of reasoning and explain the reasoning
- CCSS.Math.Content.6.EE.B
Reason about and solve one-variable equations and inequalities.
- CCSS.Math.Practice.MP8
Look for and express regularity in repeated reasoning.
- CCSS.Math.Content.6.RP.A
Understand ratio concepts and use ratio reasoning to solve problems.
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