If we know the size of the force (F) and the area over which the force is applied (A), then we can calculate pressure using

Here is the outline of a pupil’s shoe, it’s drawn on graph paper so that the area can be calculated quickly by counting the large squares. Each large square is 1 square centimetre – we counted the approximate area by considering only whole squares inside the black outline of the shoe.

Assuming a mass of 50kg, the pressure when wearing these flat-soled shoes is

The red shaded area of our photo shows the reduction in area when heels are worn. With heeled shoes, the area is reduced to approximately 1 square cm per shoe. The change in the pressure is staggering: