Multiplying Integers Lesson: Negative Times Negative, Grades 6-8

Why is a negative times a negative positive? This lesson answers it two ways before it states the rule. First, students carry a pattern past 0: 3 × (−2), 2 × (−2), 1 × (−2), 0 × (−2) go up by 2 each line, so (−1) × (−2) is 2. Then they use the distributive property, the argument the standard names: (−1) × (1 + (−1)) = 0, so (−1) + (−1) × (−1) = 0, and (−1) × (−1) must be 1.

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