Lesson objective: Fluently add and subtract numbers in different ways using a number line.

This lesson helps to build fluency with adding and subtracting numbers within 100. A number line is used here because it clearly shows how students are thinking about numbers. This work develops students' understanding that we can use addition and subtraction in many ways.

Students engage in Mathematical Practice 6 (Attend to precision) as they clearly explain to a partner how they arrived at an answer.

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