# 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

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

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

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?

You will notice the arrows go through the midpoints.

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%.

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

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

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

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

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.

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.

# 118. App of the day

Do you ever play the numbers round from the TV programme ‘Countdown’ in class?

I was on a training course the other week and whilst chatting in a break Sarah – a fellow delegate, introduced me to the free android Countdown app. It is so easy to use a 6 yr could (and does) use it.

There are quick rounds, full games and practice mode. If you choose the number practice mode, you can randomly select numbers and it will even show you the solution. So you can use Countdown as a starter without scribbling numbers on a bit of paper and only being 10 seconds ahead of the class.

Download it from the android store by searching for ‘Countdown for Android’.

# 50. When will I ever use this …

A prescription says to take 2 pills every 4 hours, but don’t take more than 8 pills in 24hrs. There are 100 pills in a prescription.

If you start taking them on the 22nd March, when do you stop taking them? Assume you start taking them at midday and are in bed by 2230.

You can’t get a more real-life maths problem than that!

# 48. Percentage book

I’ve found that copying examples and methods into a useable revision resource can be tricky for younger pupils or those with concentration issues. They don’t refer back to their notes because they are either incomplete, unreadable, unfindable in their book or just lost.

I saw instructions for making simple books from a single sheet of paper and wondered if it was worth a try.

Non calculator percentage book

Making the book
Fold a sheet of paper into eight as shown. The sample here is A4, but I used A3 in class.

Cut along the middle two quarters (blue line in the picture) and fold in half lengthways.

Fold this into an X shape.

Arrange into a book.

Instructions
Clearly label the cover – you want your pupils to find this easily.

As we filled in each page, I explained why we did each process. Because their books were larger, the bottom of their pages had questions too.

We covered 50%, 25%, 10%, 5%, 30% and the last page was a challenge/extension task: 17.5%.

The back page was left blank so that they could stick the mini-books into their exercise books.

Example