The Area of a Circle

1. The Area of a Circle Too big! Too small! Just right!

2. Recall the story of Goldilocks and the Three Bears.

3. While they were gone, a girl named Goldilocks came walking by the Bear house.� She was hungry and smelled porridge, so she decided to go into the house. First she tried Papa Bear's porridge, but it was too hot. Then she tried Mama Bear's porridge, but it was too cold. Then she tried Baby Bear's porridge, and it was just right, so sheate it all up.

4. After she had eaten the porridge, Goldilocks wanted to sit down and take a rest. First, she sat in Papa Bear's chair, but it was too high for her. Then she sat in Mama Bear's chair, but was too soft. Then she sat on Baby Bear's chair, and it was just right. She rocked back and forth on the chair, and suddenly it collapsed and broke into many little pieces. Oops!

5. After Baby Bear's chair broke, Goldilocks was exhausted, so she decided to take a nap. She went into the� bedroom and first tried to get into Papa Bear's bed, but it was too big. Then, she crawled onto Mama Bear's bed, but it was too slippery and she slid right off. Finally, she got into Baby Bear's bed. It was just right. She fell asleep right away.

6. We are going to use this idea of �too small,� �too big,� �just right� to help us make sense out of the formula for the area of a circle.

7. Let�s estimate the area of this circle.

14. Let�s summarize what we have done so far.

17. If 4 x 3 x 3 is too much and 2 x 3 x 3 is too little, then what should be just right?

18. That�s right! 3 x 3 x 3 should be just right for the area of the circle.

19. Now let�s figure out what the numbers mean.

20. �3� appears to be a very popular number in all of the expressions that we saw.

22. The radius of the circle is 3.

23. Can you guess what magical number makes the formula just right ?