Provides classroom activities for middle school math teachers to help students build foundations for algebraic thinking. The concept of balance is important to algebraic thinking. Asks the questions, "What do you think of when you see an equal sign?" Shows a seventh grade classroom teacher working through the model lesson "Cups and Tiles." Helps students understand that the equal sign means both sides are balanced, which will help them solve equations. Uses models to go from concrete to representational to abstract.