Determine which sides of your pennies attract and repel each other. The heads and tails sides should each be a different pole. Use the pennies to determine which side sticks to your circular magnets; if the tails side sticks, start your pyramid with the heads side down and vice versa.
Place 10 pennies with the magnet-repellent side down on your cardboard. Place 8 pennies on top of the first row of pennies, with each penny in the second row overlapping the edges of two pennies in the first row. Make sure the second row magnetizes to the first. Continue with rows of 6, 4, 2 and 1 penny to complete your pyramid.
Line up the four circular magnets on the cardboard square with the repellent sides up. Gently pick up your penny pyramid and set it above the magnets. If you've built your pyramid correctly, the pyramid will float above the magnets.