Next, erase the box and write an x in its place. It stands for an unknown number. It works just like the box. We don t have to use an x. We could use any other letter we want.
Many people use x and y for variables.
Be sure to provide ample examples and exercises for students with the variable or box on the right side of the equation as well as on the left. You do not want students to think that the box will appear on one side only. Continue with examples like the previous two and then with examples in which there are two addends on each side of the equation. Be sure to place the variable in different positions in the equations. Hints Students need significant practice with equations.