Use math drawings to represent subtraction with up to two decompositions, relate drawings to the algorithm, and use addition to explain why the subtraction method works

In this lesson, students continue to build their conceptual understanding of subtracting numbers within 1,000. They move from concrete to pictorial representations, as they use place-value disk drawings to model decompositions while simultaneously recording these changes in vertical form. This helps them to relate the pictorial representation to the standing vertical algorithm.