After Moses grew up, one day he saw an Egyptian man beating up a Hebrew man. When he tried to stop him, the Egyptian man was killed. Moses had to run away from Egypt.
Moses became a shepherd for many years. One day he was watching the sheep near Mount Horeb. Suddenly the Lord appeared to Moses in the middle of a bush that was burning with fire.
God spoke to Moses. First He told him to remove his sandals because he was standing on holy ground in the presence of God. Then He told Moses that he had to return to Egypt to free the Hebrew slaves.
Moses said to God, "I won't be able to convince the Pharaoh to let the sons of Israel go, and even if I do, why do you think they will follow me. Why should they believe me?
The Lord said, "Throw down your staff." Moses threw it on the ground and it turned into a serpent. The Lord said, "Now pick it up by the tail." Moses did so and the snake became a staff again!
With this sign and others Moses finally believed that God would always be with him to help him do the difficult things God had asked him to do. And so he left for Egypt.
Descriptions adapted from JesusandKidz.com