Georgia 8.MP.3
The Standard
Construct viable arguments and critique the reasoning of others.
Georgia's K-12 Mathematics Standards · Display perseverance and patience in problem-solving. Demonstrate skills and strategies needed to succeed in mathematics, including critical thinking, reasoning, and effective collaboration and expression. Seek help and apply feedback. Set and monitor goals.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students make a mathematical claim and support it with definitions, calculations, examples, diagrams, or logical steps. They examine classmates’ arguments, identify gaps, and explain whether each conclusion follows.
What Mastery Looks Like
- A student can present a clear solution with each step supported by a rule, definition, diagram, or calculation. The student can find an unsupported step in another argument and use a counterexample or correction to challenge it.
Common Misconceptions
- Students may think a correct answer is enough, even when no reasoning is shown. They may accept an argument because it matches their answer. They may also use one example as proof that a claim is always true.
How to Assess It
- Exit ticket: “Jordan says 3(x + 2) = 3x + 2 because multiplication only affects x. Identify the error, correct it, and justify your correction.”
Lesson moves
Ways to Teach It
Give pairs algebra tiles and two written solution paths; students model each path, circle the invalid step, and explain the error.
Post the claim, “Every linear equation has one solution”; students write a response, then discuss examples that support or disprove it.
Run an Evidence Match game: teams pair claim cards with proof, example, or counterexample cards, then defend each match.
Compare two phone-plan tables and graphs; students decide which claim about cost is accurate and defend it with numbers.
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