Have you heard people talking about 3D? The D stands for dimensional. A flat shaped like, a rectangle has two dimensions, length and width. But a solid like this rectangular prism is 3D. It has a third dimension, its height. The height is what we were measuring when we counted the layers upwards and again because we built the shape from centimeter cubes. We know that each cube side measures one centimeter. So the height of the solid is two centimeters.

To find the volume of the rectangular prism, we multiply the length by the breadth. To find the area of the two dimensional figure at the base and then measure the 3D solid by multiplying again by the height. Length times width times height would give you the volume of any rectangular prism. And once you enter the third dimension your measurements have to be in cubic units like these cubic centimeters.