Label the length, height width of the rectangular prism and label them with letters either l, h or w
Then label the three sides that meet at the corner
Then look at the six faces of the prism, they are top and bottom, front and back and finally left and right face with each of the same size
Then take time to find the area of the bottom face, then the top face and finally the left and right face
Then add each face together and the unit will be square inches.
Then simplify it— 2lw + 2wh + 2lh— which is the area of a rectangular prism
Then factor out the two 2(lw + wh + lh)
