From Sydney, Grade one: "How do rockets blast off?

One Possible Answer:A rocket is like a tube that is open at one end and closed at the other. The rocket is filled with fuel. When the fuel burns, gasses expand and go out the open end. When this happens, the moving gasses push the rocket upwards. I found this in The New Book Of Knowledge in King Edward School Library.

Other questions:

• What kind of fuel do they use in rockets?
• What is the biggest rocket that has ever been launched?