3-4

I3: Generate examples illustrating that when something is pushed or pulled, it exerts a reaction force.

Curriculum Organizing Questions	What causes objects to move? What is a force? How can you change the motion of this object by using a force? When you push or pull an object, what happens?
Elaboration	Anytime that you push or pull on something, there will be a push or pull back From a scientific point of view forces always "come in pairs." For every force there is an equal and opposite reaction: a mug on a table exerts a force on the table; the table exerts an equal and opposite force on the mug. Driver pg. 151.
Specific Ideas	The position and motion of objects can be changed by pushing or pulling. NSES B2c. The size of the change is related to the strength of the push or pull. NSES B2c.
Developmental & Instructional Implications	The concept of a reaction force is a difficult concept to teach at this age level. Developmentally more appropriate at the high school level.
Examples	Let the air out of a balloon and the balloon goes up. Use balloon rockets on strings.

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