PRESENTATION OUTLINE
Newton's first law of motion states that an object's motion will not change unless an unbalanced force acts on the object.
If the object is at rest it will stay at rest. Newton's first law is also called the law of Inertia. Inertia is the tendency of an object to resist a change in it's motion.
Real life example
A body on Earth would have that same mass on the moon, but you would weigh less on the moon because gravity is less on the moon as the gravity on Earth.