Volume of a Prism

Cut a loaf of bread into slices. Every slice has the same shape. Put the slices back together and you have the loaf again. A box is like that too, so a box is a prism.

A solid with the same slice all the way through is a prism. It has two equal ends, joined by flat faces. Volume of a prism = area of the end × length.

The legs of a right triangle are the two sides at the right angle. A right triangle end with legs 4 and 3 has area $\frac{1}{2}\cdot 4\cdot 3 = 6$. So a prism 6 long holds $6\cdot 6 = 36$.