Comparing the Weight of Objects

Weight is the measure of the force (due to gravity) that is acting on an object.

Mass is the measure of the amount of matter in an object.

  • When we use a scale to find a measurement, we refer to the measurement as weight.
  • When we use a balance to find a measurement, we refer to the measurement as mass.

These words are used to describe the weight of something:
“light, lighter, lightest” and ”heavy, heavier, heaviest”.

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  • Which is heavier, the sugar or the cotton wool?
  • Which is lighter, the sugar or the cotton wool?

Establish that the sugar is heavier than the cotton wool, and that the cotton wool is lighter than the sugar.

  • Which is larger, the packet of sugar or the cotton wool?

Hold the two objects side by side to show that the packet of cotton wool is larger than the sugar, and that the sugar is smaller than the packet of cotton wool.

‘The packet of cotton wool is larger. The packet of sugar is heavier.’

Sometimes smaller things are heavier than larger ones.

 

SUMMARY FOR STUDENT

  • We use a balance to find out which of two things is heavier.
  • The side of the balance that goes down is the heavier side. The side that goes up is the lighter side.
  • We can balance objects using bricks. The more bricks that we need to balance an object, the heavier it is. So if a book weighs the same as 12 bricks, and a ball weighs the same as 5 bricks, the book is heavier than the ball.
  • Sometimes smaller things are heavier than larger ones. For example, our bag of sugar was heavier than our large packet of cotton wool.

 

  • The balance shows us which object has more mass because the object with more mass pushes down the side of the balance it is on further than the object with less mass.
  • What is happening if the balance is level and neither side goes down?
  • The objects have the same mass.
  • The sides are at the same height because there is not an object with more mass to cause one end of the balance to push down.

Example of Weight/Mass Graphic Organizer

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