Mix air dry clay, dirt or sand, pine straw or hay and one tablespoon of water in a large mixing bowl using your hands. Play with the amounts of each ingredient you use in order to find a consistency that works for you. Add water one half teaspoon at a time if your mixture is too dry or hard to work with.
Form the mixture into a ball to test the consistency. If the mixture does not stay in a tight ball, you may have added too much water. Try adding a bit more sand or dirt to dry up the water. The mixture should be relatively stiff but you should still be able to manipulate it easily using your hands.
Transfer the mixture to a sheet of wax paper when you achieve the right consistency. Spread the mixture evenly using a rolling pin. Rolling the cob will ensure that all of the air bubbles work out of the mixture, minimizing the chance of cracks in the finished bricks. Make sure that the height of your rolled mixture does not exceed about one half inch.
Create bricks using a knife and ruler. For most children's projects, bricks can be a rectangular shape of about one inch by two inches.
Allow the bricks to air dry overnight. You may place them in the sun to speed up the drying process, but heat is not necessary for air dry clay. Remove the bricks from the wax paper using a spatula if necessary.
