Simple machines are tools with few parts that make work easier by changing the direction or magnitude of force. Gravity pulls everything on Earth downward and the strength of gravity depends on the size of the planet. Friction occurs when two objects rub together and the amount of friction depends on the surfaces, with ice having less friction than car tires. Force is a push or pull, like gravity acting on an apple falling from a tree, that causes an object to move or change motion.

2. Simple Machines
 A simple machine is a tool with a small amount of parts
for example a screw driver would be a simple machine
because it has a small amount of parts.

3. Gravity
 Gravity holds every thing down to earth. If there was no gravity everything would
move and float forever. The bigger the planet the more gravity it has and the
smaller the planet the less gravity it has.
 It will pull you down when you jump

4. Friction
 Friction is what happens when two objects rub together.
Friction makes fire. On ice there is less friction and on a car
tire there is more friction.

5. Force
 Force is a push or a pull in gravity to make a object move. If
a apple falls from a tree a force is acting on it.