| $ Store Activity
Name: |
Spiky Ball Spikes
|
| Concepts / Skills
addressed: |
counting, graphing,
circumference, diameter,
|
| Approximate Grade
Range: |
6th - 8th ?
|
| Materials: |
Spiky massage balls, ruler
|
| The General Idea:
|
There is a relationship between
the radius and circumference of a circle (C=2*pi*R). There are
many traditional investigations into this relationship. Here we
have an investigation that gets at the same relationship but that is
not quite so traditional.
The ball is divided into two halves and you can see a line that runs
all the way around the ball, like the equator of the earth. If
that line is the equator then look where the north (or the south) pole
would be. There is a blank spot there, presumably where the ball
was inflated. All of the spikes on the ball can be seen as making
concentric rows around this pole. There are 6 rows in each
hemisphere of the balls I found. Each row, because it is further
down toward the equator, (at a different latitude?) has a different
number of spikes. How is the number of spikes related to its row
number? This is one of many questions that can be investigated
with this simple object.
|
Extensions:
|
You could do the same sort of an
investigation with a basketball, a soccer ball, a baseball, etc.
It gets a little different with a football....
|
| Links: |
|
Author:
|
Mark Roddy
|
