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Science project idea

Fraction pizza circles with a spinner that matches equal parts

Circles cut into 2, 3, 4, 6, 8 and 12 equal slices show that 1/2 is the same amount as 2/4, 3/6, 4/8 and 6/12, and that two slices of 1/3 plus one of 1/6 make 5/6, which is less than one whole pizza.

Make it yourself8 numbered steps, the materials and the science, all free.Go to the stepsGet a ready-made kitReady-made models, kits and spare parts in the store under Maths.Browse MathsAsk on WhatsAppAsk the head office whether a model or kit for this idea is available.Send a message

What it shows

Circles cut into 2, 3, 4, 6, 8 and 12 equal slices show that 1/2 is the same amount as 2/4, 3/6, 4/8 and 6/12, and that two slices of 1/3 plus one of 1/6 make 5/6, which is less than one whole pizza.

The science

A fraction names equal parts of a whole. 1/4 means the whole is cut into 4 equal parts and we take one. Equivalent fractions are the same amount cut differently: 2/4 covers the same space as 1/2. Because all six circles are the same size, pieces from different circles can be laid on each other to compare and to add.

Materials

Cost: under Rs 50. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.

  • Six paper plates or card circles of the same size
  • A protractor and ruler
  • Coloured sketch pens or paints
  • A split pin or drawing pin for the spinner
  • A cardboard arrow
  • A tray or board to lay out the pieces

Safety

For this project: An adult must help with the split pin and the scissors.

Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.

All the safety rules

Step by step

8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.

  1. Mark the centre of each circle and use the protractor to divide them into equal slices: 180 degrees for halves, 120 for thirds, 90 for quarters, 60 for sixths, 45 for eighths and 30 for twelfths.

  2. Colour each circle a different colour, cut out the slices and write the fraction on every slice, such as 1/6.

  3. Make the spinner: a seventh circle divided into twelve sectors labelled with fractions, with a card arrow on a split pin at the centre.

  4. Lay a 1/2 slice on the board and cover it exactly with two 1/4 slices, then with three 1/6 slices, then with six 1/12 slices.

  5. Spin twice and add the two fractions by laying the slices together on a blank circle, for example 1/3 and 1/6 fill half a circle.

  6. Compare 2/3 and 3/4 by laying them side by side on blank circles; 3/4 leaves a smaller gap, so it is bigger.

  7. Write the equivalences you found in a table on the board: 1/2 = 2/4 = 3/6 = 4/8 = 6/12.

  8. Keep each colour in its own envelope so pieces are not lost between shows.

What you should see

Any 1/2 slice is covered exactly by 2 quarters, 3 sixths, 4 eighths or 6 twelfths, and the spinner lets a visitor add two fractions by laying the slices on an empty circle.

Viva questions

A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.

1How many twelfths make one third?

Four, because 4/12 = 1/3.

2Which is bigger, 2/3 or 3/4?

3/4. On the board it leaves a smaller gap in the circle.

3What is 1/2 plus 1/4?

3/4.

4Why must all the circles be the same size?

A fraction is a part of a whole, so to compare parts the wholes must be equal.

Free ebook: Viva Questions for Science Projects

Take it further

Add a circle cut into tenths and show 1/2 = 5/10 = 0.5 to link fractions and decimals.

Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.

Free ebooks for this project

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