Exploring Newton's First Law: Inertia Kit. Students investigate inertia by observing a marble's motion around a specially designed circular track, and then predict what path it will follow when a section of the track is left open. They discover that once the marble leaves the confines of the track, it moves in a straight line path. Students will also investigate how, or if, changing the mass or the marble changes the results. In Part 2, students complete a reading about inertia and Newton's first law of motion. The kit accommodates unlimited classes, each with 6 groups of 4 students.