sentence: Rocket motors come in many different sizes, and they are indicated by a code on the motor.
sentences_before: A 'model rocket' is a miniature rocket. They are not launched by the government or a space program. They are used by people interested in rockets. Even though it seems dangerous, it is quite safe and is a way many people start getting interested in rockets and space exploration.
sentences_after: There are also many ways for the rocket to fall back down after it is ignited. Some of them use parachutes.
concept_name: rocket motor
headings: Model rocket
categories: Rockets