standard_description: Prove that, given a system of two equations in two variables, replacing one equation by the sum of that equation and a multiple of the other produces a system with the same solutions.
problem_activity: Stage 1: Within 10
Required Preparation
Materials to Copy
Blackline Masters
Number Puzzles Addition and Subtraction Stage 1 Gameboard
Number Puzzles Digit Cards

Narrative
Students work together to use digit cards to make addition and subtraction equations within 10 true. Each digit card may only be used one time on a page.


aligns: no