Spacecraft Launches Create models of the Tuesday and Wednesday spacecraft launches to explain the difference in speed. Use a magnet to represent the spacecraft in each launch. Use the symbols shown in the Key in your models.

scientific laws are the result of testing theories and proving them to be facts.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.