The first way is easy if you have a container that has markings to tell
how full it is. You fill it partway full with water and write down how
much water is in the container. Next, put the ball into the water. You
need get the ball totally under the water, so you might have to push it
down with your finger. Be careful not to put your finger in the water
too or else your answer will be a bit wrong. Write down the level of
the water now. Subtract the 2 numbers and you'll have the volume of the
The second way is like the first. Do this in a sink because it can
get a little messy. Fill up a container to the very top. You'll need to
measure this so you know how much you have. Then put the ball in and
let all the extra water flow over the top and into the sink. You'll
probably have to push the ball in like before. Measure the water you
have left and subtract it from what you had to begin with. That's your
The last way is the easiest, but won't be as easy to see. You can
find the volume using math. Measure how wide the ball is. This is
called the diameter. Half of the diameter is called the radius. Then
use the formula: Volume=(4/3)*pi*radius^3.
pi is a number that is about 3.14
the little ^3 means to multiply the radius times the radius times the radius (r*r*r).
This won't be exact because it only works for perfectly round balls and styrofoam balls tend to have bumps on them.
(republished on 07/18/06)