CCSS.Math.Content.3.MD.C.7.c

Use tiling to show in a concrete case that the area of a rectangle with whole-number side lengths 𝑎 and 𝑏 + 𝑐 is the sum of 𝑎 × 𝑏 and 𝑎 × 𝑐. Use area models to represent the distributive property in mathematical reasoning.