3.MD7c 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.
I am discovering (as are the math teachers in most of the states in America) that the Common Core standards are MUCH more complicated than they look on paper. We were warned, right? Now I'm a believer!
ANYWAY, we have done a ton of activities to become more familiar with the distributive property.
First, we used this lesson on the distributive property where students used Fruit Loops to create arrays. I began introducing problems like 4 (3 x 4) and we made arrays to correlate with each of the distributed facts.
(2 x 1) + (2 x 5)
(2 x 2) + (2 x 4)
(2 x 3) + (2 x 3)
(2 x 4) + (2 x 2)
(2 x 5) + (2 x 1)
We also split the array horizontally into (1 x 6) + (1 x 6).
Students wrote down all of these arrangements on a recording sheet.
4 (2 + 4) = (4 x 2) + (4 x 4)