Forces and Motion for Grade 3

Objects move when forces act on them. A force is a push or a pull, and different forces can change how an object moves. Grade 3 students begin to use observations and simple investigations to explain motion and predict patterns.

A Force Is a Push or Pull

A force can start motion, stop motion, or change motion. When you kick a ball, you apply a force. When you pull a wagon, you apply a force. Forces are part of everyday life.

Students should connect the word force to actions they can see and feel.

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Example Pushing a toy car makes it start moving across the floor.

Forces Change Motion

Motion means movement. A force can make an object speed up, slow down, stop, or change direction. The same object may move differently depending on how strong the push or pull is.

Observing these changes helps students connect cause and effect.

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Example A harder kick can make a soccer ball travel faster or farther.

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Tip Use the words speed up, slow down, stop, and turn when discussing what a force does.

Balanced and Unbalanced Forces

Balanced forces do not change the motion of an object in one direction because the pushes or pulls are equal. Unbalanced forces do change the motion because one force is stronger than the other.

Students do not need advanced formulas. They need clear examples and simple investigations.

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Example If two teams pull a rope equally, the rope may stay mostly in place. If one team pulls harder, the rope moves.

Friction Affects Motion

Friction is a force that happens when surfaces rub against each other. Friction can slow objects down. A toy car may roll farther on a smooth floor than on carpet because the surfaces are different.

This helps students see that motion depends on more than one factor.

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Example A book slides more easily across a smooth table than across a rough mat.

📝 Key Vocabulary

Force

A push or a pull

Motion

Movement

Friction

A force that slows motion when surfaces rub together

📐 Standards Alignment

3-PS2-1 NGSS

Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.

3-PS2-2 NGSS

Make observations and measurements of an object's motion to provide evidence that a pattern can be used to predict future motion.

🔗 Glossary Connections

Force A force is a push or pull that can make something move, stop, or turn. Motion Motion means that something is moving. Friction Friction is a force that can slow things down when they touch and rub. Balanced Force Balanced forces are pushes or pulls that are equal, so motion does not change much in one direction. Unbalanced Force Unbalanced forces are pushes or pulls that are uneven, so something speeds up, slows down, stops, or turns.

⚠️ Common Mistakes to Watch For

Thinking motion keeps changing without any forces involved
Assuming all pushes and pulls have the same effect
Forgetting that friction can change how far an object moves

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Real-World Connection Children use force and motion when they ride bikes, throw balls, push carts, use playground equipment, or slide objects across surfaces.

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Fun Fact! Athletes often choose smooth or rough surfaces on purpose because friction changes how equipment moves.