Anchor Phenomenon Ideas: You could begin this unit with a simple question: Why doesn't the moon come crashing into Earth? Or, you could simply share two pictures with students - one of our moon and one of an asteroid - and ask them the describe differences. Why does one orbit Earth and the other potentially crash into Earth? The discussion will most likely lead to more questions - which is great!
This TED-Ed about how far would you would have to go to escape gravity will also generate many questions!
Tips and Tricks: As students spin their string and ball model in a circle for question four, point out the balance that exists between the forces of inertia (the ball's velocity) and gravity (the string). Help students make the direct connection between their hand as the sun and the ball as Earth. The same model can be used with their hand representing Earth and the ball representing the moon.
Allow students to play with the Gravity and Orbits PhET simulation as they answer question five. They often learn more through play than our direct instruction.
Enrichment Ideas: Susan Beth Pfeffer's young adult series, Life as we knew it, tells the dystopian story of life after an asteroid hits the moon and moves it much closer to Earth. Middle schoolers love these four books and we cannot keep them on our classroom shelves! This is an excellent way to connect real science with science fiction. Could this really happen?
Share excerpts with the whole class or offer copies of the books for kids to read as they finish the mini unit. See our Multiple Intelligences Book Project for more ideas!