Here are three action-reaction force pairs involved in doing homework:

1. Action: Hand pushing down on pencil

Reaction: Pencil pushing up on hand

* Object exerting force: Hand

* Object receiving force: Pencil

2. Action: Pencil pushing down on paper

Reaction: Paper pushing up on pencil

* Object exerting force: Pencil

* Object receiving force: Paper

3. Action: Fingers pushing on book

Reaction: Book pushing on fingers

* Object exerting force: Fingers

* Object receiving force: Book

Important Note: Action-reaction forces always act on *different* objects. They are equal in magnitude and opposite in direction.