In this lesson, we are extending the concept of area from two-dimensional figures to three-dimensional solids. Just as the area of a rectangle is determined by multiplying its length by its width, we can apply a similar approach to a rectangular prism. A rectangular prism is a three-dimensional figure with length, width, and height. In this case, the base of the rectangular prism is a rectangle that measures 8 units long and 5 units wide, just like the rectangle from the warm-up. The height of the prism adds a third dimension, which is 3 units. The volume of this rectangular prism can be found by multiplying the area of the base (8 units by 5 units) by the height (3 units), giving us the total space enclosed within the prism. This extension to three dimensions allows us to measure and understand the volume, or the amount of space inside solids.