The school principal just entered your classroom and announced, "All school field trips must be canceled due to budget cutbacks."    After the moans and groans subsided, he continued.  "I know that you are really disappointed but, this is a big problem for the students in third grade.  They must take a test over forces, motion and simple machines and their trip to the Physics Museum was canceled.  The third grade teachers have asked for your help.  They would like you to create an interactive museum full of experiments about forces, motion, and machines in our school cafeteria.  The third grade students would tour the museum with you as their guide.  It is very important that the third graders learn as much as possible about these topics so that they will score well on the test. Their test has only one question, but it is a really hard question: How do forces and motion affect the Earth and everything on it?"

"Will you help our third graders do well on the test?"