Unit 9 Contents

4. Think of a rule that gives the size in squares, S, for an Add Three Alligator of any age, A. Write the rule both in words and as a number sentence using A and S. This kind of number sentence is called a formula.
5. Use your formula to calculate the number of squares a 25-year-old Add Three Alligator will have. Did you get the same answer you got for Question 3C? If not, explain why not.
6. How old is an Add Three Alligator that has 66 squares? Show or tell how you solved this problem.
7. If an Add Three Alligator has 100 squares, about how old is it? Show or tell how you solved the problem.

Four Arm Starfish

A Four Arm Starfish grows like this:

1. Use square-inch tiles to build a model of the Four Arm Starfish up to at least age 8. As you add tiles for each year of age, record the data in a table.
2. Plot your data using the same set of axes you used for the Add Three Alligator.
3. Draw a line that goes through all of the points. Extend your line until it meets the vertical axis.
4. Think about the point where the line meets the vertical axis. What does it say about the Four Arm Starfish? Does this make sense?