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Topic: cross-sectional pictures
Replies: 1   Last Post: Feb 4, 1998 11:18 AM

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Larry Riddle

Posts: 10
Registered: 12/6/04
Re: cross-sectional pictures
Posted: Feb 4, 1998 11:18 AM
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Sheila King wrote about slicing a hard boiled egg to illustrate the
idea of cross-sectional areas for computing a volume. I have found
that an eggplant also works quite well for this. I bring a large
eggplant and a sharp knife to class that I use to cut the eggplant
into slices. If you do your slices carefully enough, most of them
will be rather close to having a circular cross section that is
almost equal on each side (the ends cause a problem, so I usually
cut them off first). I give each student a slice and a ruler and ask
them to approximate the volume of the slice. We then use the
individual estimates to get an estimate for the volume of the
eggplant. Before class I use the old "how much water is displaced"
method to get another estimate for the volume. Unlike Sheila's egg,
however, no one has ever volunteered to eat the eggplant when class
was over.

Larry Riddle

Larry Riddle |
Dept of Mathematics | 404-638-6222
Agnes Scott College | 404-638-6177 (fax)
Decatur, GA 30030 |

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