ABSTRACT
When working on the big ideas of algebra in the primary grades, it is very important that students have a chance to reason about situations and numbers. Algebraic thinking must be developed from the beginning of school. In first grade, students are also playing around with the commutative and associative properties. These are fundamental building blocks to later algebraic work. This chapter explores odd/even numbers, arrays, missing numbers, and true/false equations. Isler, Stephens, and Kang posit that in elementary school teachers need to develop the four algebraic thinking practices of generalizing, representing, justifying, and reasoning with mathematical relationships. Teaching arrays is important. This is a foundation for students understanding multiplication. Working with the equal sign is always tricky. It has to be done with hands-on activities. Students need to actually build the facts so that they can see what the math is. They should absolutely act out the problems.
