**Title:** Hopping Backward on the Number Line

**Description:**
In this lesson, one of a multi-part unit from Illuminations, students generate differences using the number line model. Because this model highlights the measurement aspect of subtraction, it is a distinctly different representation from the models presented in lessons one and two. The order property for subtraction is investigated. At the end of the lesson, children are encouraged to predict differences and answer puzzles involving subtraction.

**Standard(s): **

[MA2015] (2) 19: Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points corresponding to the numbers 0, 1, 2, ..., and represent whole-number sums and differences within 100 on a number line diagram. [2-MD6]