Geometry: Surface area & volume of solids

Every 3D object has two major measurements: surface area and volume. Surface area is the total area of all the flat faces on the outside, while volume is the amount of 3D space contained inside the shape.

Let's look at volume first! Imagine filling a rectangular box with unit cubes. The total number of cubes that fit inside tells us the volume, calculated by multiplying length times width times height.

Now, let's look at surface area! Imagine unfolding a cardboard box flat onto the table. This flat representation is called a 'net', and adding up the area of all these flat shapes gives you the total surface area.