Explain how a rocket can propel itself using Newton's third law.

"For every action there is an equal an opposite reaction" ... or something like that right? You push on the ground and the ground "pushes" back. If you hit a wall then you'd feel the force as well. Maybe not so clearly, this is how rockets propel too.

Rocket fuel has materials in it that act as the "ground" or the "wall", in that when the materials are expelled [with some great force] from one end of the rocket, an opposite force propels the rocket forward or upward. So a rocket's movement is basically dependent on the "equal and opposite reaction" described in Newton's Third Law of Motion.