Newton’s laws of motion are simple to state, and sometimes teachers mistake the ability of students
to recite the three laws correctly as evidence that they understand them. The fact that it took such a
long time, historically, to codify the laws of motion suggests that they are not self-evident truths, no
matter how obvious they may seem to us once we understand them well. Much research in recent
years has documented that students typically have trouble relating formal ideas of motion and force to
their personal view of how the world works. These are three of the obstacles: