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## Number Talks

Topics: Mental math, numerical fluency; argument & critique Materials: White board or projector Time:5 – 15 minutes Common Core: Variable, but especially MP3 This mental math routine creates powerful positive habits for students. Why We Love Number Talks Number talks don’t replace other instruction, but they are a powerful complement to it. They get all students involved, help them strengthen fluency, intuition, …

## Counterexamples

Topics: logic, deduction, mathematical argument, communication Materials: None Recommended Grades: K, 1, 2, 3, 4, 5, 6, 7, 8 Common Core: Variable, but especially MP3 Proving the teacher wrong. Rigorously. Why We Love Counterexamples Every kid loves to prove the teacher wrong. With Counterexamples, they get to do this in a productive way, and learn appropriate mathematical skepticism and communication …

## 1-2-3 Nim on a 10-Frame

Topics: logic, patterns, addition to 10, counting to 10, subtraction Materials: One 10-frame and at least ten counters per pair of students Recommended Grades: K, 1 Common Core: K.CC.A.2, K.CC.B.4, K.CC.B.5, K.OA.A.1, K.OA.A.2, K.OA.A.4, K.OA.A.5, 1.OA.B.4, MP1, MP7 How to Play Players take turns placing one, two, or three counters on the open squares of a 10-frame. Whoever fills up …

## 1-2 Nim

Topics: logic, patterns, addition, counting, subtraction, divisibility and remainders (optional) Materials: Counters (tiles, beans, pennies, etc.) or paper and pencil Recommended Grades: K, 1, 2, 3, 4 Common Core: K.CC.A.2, K.CC.B.4, K.CC.B.5, K.OA.A.1, K.OA.A.2, K.OA.A.5, 1.OA.B.4, 1.OA.C.5, 2.OA.B.2, 3.OA.D.9, 3.OA.A.2, 3.OA.A.3, 4.OA.C.5, MP1, MP2, MP3, MP5, MP7, MP8 You can take one or two counters from the pile. How do …