Offers a brief and clear introduction to simple machines: what they are, their parts and what they can be made of, how they work and how we use them to apply the forces of pushes and pulls to move, lift, make or break th...Offers a brief and clear introduction to simple machines: what they are, their parts and what they can be made of, how they work and how we use them to apply the forces of pushes and pulls to move, lift, make or break things.