What is a Torus?

Date: 11/30/1999 at 10:58:11
From: Jennifer Hemmerlein
Subject: How can I explain what a torus is?

Hi,

I am currently researching three-dimensional shapes for a program for 
children, and I'm having difficulty explaining in plain terms exactly 
what a torus is. I've looked in the dictionary and at your 
mathematical explanations of a torus, but is there a good way to 
describe a torus to a kid?

Thanks,
Jennifer

Date: 11/30/1999 at 23:08:20
From: Doctor Douglas
Subject: Re: how can I explain what a torus is?

Hi Ms. Hemmerlein,

The way I would explain it to a kid is to imagine a doughnut, or a 
bagel. Strictly speaking, it is just the surface of the doughnut (i.e. 
where the powdered sugar is).

One interesting property of a torus is that it is a "connected" 
surface, or a "connected" shape. If you cut through the doughnut with 
a knife (once),  it stays in one piece (assuming you chose the right 
cut - it's possible to cut it so that it does fall apart). No matter 
how you cut through an orange (which of course, is a sphere), though, 
you end up with two pieces.

I hope that helps, and please write back if you need a more detailed 
explanation.

- Doctor Douglas, The Math Forum
  http://mathforum.org/dr.math/