To compare lengths, line the objects up so they all start at the same place, then see which one reaches furthest. If they do not start together, look at both ends. To compare how much jugs hold, pour each one into the same-sized glass and compare the water levels: a tall jug is not always the one that holds most. To compare masses, use a balance. The heavier side goes down. With two balances, put all the objects in order to find the heaviest or lightest.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- longest
- reaches the furthest when things start at the same line
- holds the most
- has room for the most water or sand
- heaviest
- pushes a balance down the most
Worked examples
Three ribbons start at the same line. Red is 7 squares long, blue is 5 and green is 9. Which ribbon is the longest?
- 1.They all start together, so compare where they end.
- 2.Green reaches furthest: 9 squares.
= green
Three jugs are poured into the same-sized glasses. Jug A fills its glass to 4 marks, jug B to 7 marks and jug C to 5 marks. Which jug holds the most?
- 1.The glasses are the same, so compare the water levels.
- 2.Glass B has the highest level.
= B
Balance 1: the car is heavier than the ball. Balance 2: the block is heavier than the car. Which toy is the heaviest?
- 1.The car beats the ball, and the block beats the car.
- 2.So the block is heavier than both.
= block
For parents
Method: Line up and compare
What to say: Do they start at the same place? Which side of the balance went down?
Common mistakes:
- Mixes up the comparison words and picks the shortest when asked for the longest (or the most and least).
- Judges length by how thick or big a ribbon looks, so picks the thickest as the longest.
- Compares only where the ribbons finish, ignoring that they start in different places.
- Thinks the tallest container holds the most (or the shortest holds the least), ignoring how wide it is.
- Assumes the biggest-looking object is the heaviest (or the smallest the lightest) instead of reading the balances.
- Reads a balance the wrong way round, thinking the side that goes up is the heavier one.
- Uses only one balance and ignores the other, so does not put all three objects in order.