# The Cuboid The cuboid is also referred to as a rectangular prism.  If your student does not understand why a cube, is also a prism I highly recommend you go to our explanation.

To be comfortable calculating volume and surface area, your child should be comfortable with multiplication as well as addition.

## Surface Area of a Cuboid We know that a cuboid is made up of six rectangular faces. We also know that these six faces come in three pairs.Looking at the image to the left we can see the:area of the front face is: b x h (bh) This is the same as the area of the back face so we multiply it by 2:2bhWe can see the area of the side face is: l x h (lh)This is the same as the other side of the cuboid so we multiply it by 2: 2lhWe can see the area of the bottom face is:l x b (lb)This is the same as the top face, so we multiply it by 2:2lb

The surface area is the area of all the shapes making the three dimensional shape, so we must add all these areas together:

2lh + 2lb + 2bh Units Squared

## Volume of a Cuboid Looking at this image, we can see that there are three individual measurements on a cuboid.LengthBreadth/WidthHeightThe volume is:Length x Breadth x Heightor to abbreviate it further:V = lbh Units Cubed