Thread Academy

Changing Shape

Exploring how pushes and pulls can squash, stretch, bend and twist objects.

  • Define and explain Changing Shape in your own words
  • Use key terms such as force accurately
  • Apply what you have learned to new examples and questions
  • Avoid the common mistakes learners make with this topic

This lesson focuses on Changing Shape: exploring how pushes and pulls can squash, stretch, bend and twist objects.

Definition: Changing Shape

Exploring how pushes and pulls can squash, stretch, bend and twist objects.

Key ideas

Friction opposes motion

When a toy car rolls across carpet it slows down much faster than on a smooth floor, because the carpet creates more friction. Friction always pushes back against the direction of movement. Without friction, walking on ice would be impossible — your shoes would just slide.

Gravity always pulls down

Drop a ball and it falls to the ground because Earth's gravity pulls it downwards. Gravity acts on everything, which is why what goes up must come down. It even keeps the Moon circling the Earth instead of drifting away.

Key term — force: A push or a pull. Forces can make things move, stop moving, change direction or change shape.

Which way will it move?

A toy boat floats in a paddling pool. Mia pushes the back of the boat gently with her hand. What happens?

A push acts on the boat in the direction Mia's hand moves. The water pushes back only a little, because water is smooth and slippery. The boat moves forwards, away from Mia's hand. If she pushed harder, the boat would move faster.

Answer: The boat moves away from Mia, in the direction of the push.

Common mistakes
  • Saying gravity pushes things down Gravity pulls things towards the Earth — the Earth attracts the object, so 'pull' is the correct word.
  • Believing a push has to touch something Magnets can pull metal objects without touching them, and gravity pulls without touching too.

Practice

Name the force that pulls a dropped apple to the ground.
It comes from the Earth.

Gravity.

A marble rolls across a smooth table and falls off the edge. Which force makes it fall?
It acts downwards everywhere on Earth.

Gravity pulls the marble downwards once it is no longer supported by the table.

Kicking a football is an example of a push or a pull?
Think about which way your foot moves the ball.

A push — your foot shoves the ball away from you.

Why does a sledge slow down on flat snow?
Two surfaces are rubbing together.

Friction between the sledge and the snow opposes its motion and slows it down.

Quick check

Changing Shape — quick check

Which of these best defines "force"?

A push or a pull. Forces can make things move, stop moving, change direction or change shape.

Does a bigger push make a toy car travel further?

Yes — a bigger push gives the car more speed, so it travels further before friction stops it.
Key takeaways
  • Changing Shape: exploring how pushes and pulls can squash, stretch, bend and twist objects.
  • Friction opposes motion: When a toy car rolls across carpet it slows down much faster than on a smooth floor, because the carpet creates more friction.
  • magnet: An object that can pull certain metals towards it without even touching them.
  • Watch out for: saying gravity pushes things down
← Starting and StoppingFriction: Friend or Foe? →Back to Grade 7 chaptersRelated resources →