205. Percentages cubed

This neat little activity combines nets of cubes with non-calculator percentages. It doesn’t necessarily replace teaching basic percentages, but it is a good starting point.

Objectives

  • To understand the link between different percentages.
  • To construct a cube, using a 2D net.
  • To calculate percentages.

Equipment
Pre-printed nets of cubes on card
Scissors
Glue
Felt-tip pens

Task 1
Cut out the net of the cube and mark the midpoint of each edge, ensuring matching points on the joins.

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The matching points are important later on. Fold in both directions along each line.

Task 2
Label the middle square 100%.
Draw horizontal and vertical arrows going away from it with divide by 2, 4, 10 & 100. What percentages should go on these squares?

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You will notice the arrows go through the midpoints.

Task 3
After your class have identified the squares as 50%, 25%, 10% & 1%, ask your class how these are linked.

This bit wowed my class.

Draw a vertical line up from 50%.
Label it divide by 2.
Draw an arrow coming in from the left of the 25%.

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What happens if you fold the cube up?
The arrow joins up! This is why you need the midpoints.

Task 4
Ask your class to complete the labels linking the other percentages.

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Task 5
You should have one empty square. Label this 5%.

Ask your pupils to complete their arrows. They can be completed with divide or multiply.

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You will notice that mine is colour coded, based on the original percentage in each calculation.

Task 6
Glue the 5% square flap to the 25% square. This allows you to temporarily tuck in the other flaps, whilst allowing the cube to be folded flat to go in a book.

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Task 7
Give pupils a starting number eg 360. This represents 100%.
By following the arrows on the cube, they can work out all these percentages quickly and efficiently.

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  1. Pingback: 7 Days of Maths: MathsSandpit.co.uk #7 | Solve My Maths

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