Click the green flag. You will be asked to enter a start number. Type a number in the box on the screen. The pyramid will fill with more numbers. Do this several times. Now, see if you can predict what the top number will be before you press enter (or click on the check mark). Were you correct? Now show this to a friend. Ask them to enter a number and tell you what it is. Turn around so you can't see the screen. Tell them what the top number will be when they press enter. Challenge them to figure out the algebra, like you did!
This is the third in a series for use in engaging students in problem solving and algebraic thinking.
