What goes up mush come down … as long as you aren’t floating in space, that is! So let’s explore the concepts of gravity. In this chapter, the lesson for grades K–2, through several activities and readings, students learn that the force of gravity is what gives thing weight, In the lesson for grades 3–6, students predict how different games and toys would work without gravity and then check their predictions by watching videos of the toys and games in action on the International Space Station (ISS) and the space shuttle.