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What Makes a Good Resource: Chocolate Bar Fractions


Created on 18 August 2010 by ncetm_administrator
Updated on 09 March 2018 by ncetm_administrator
What Makes a Good Resource

Chocolate Bar Fractions

chocolate bars
 
1
1/2 1/2
1/4 1/4 1/4 1/4
1/5 1/5 1/5 1/5 1/5
1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10
 

Resource description:

A set of four laminated cards with a picture of a chocolate bar on the first side, and three fraction walls on the other sides

Teacher comment:

I developed this resource because some of the children in my Year 2 class were struggling with the concept of fractions and sharing equally. They had previously found halves and quarters of shapes and used counters and various objects such as fish, marbles and buttons for sharing activities. But they couldn’t see the link between half of a shape and half of an amount.

How can I link finding half of a shape to finding half of 6 objects? How could I build in time to discuss and practise this with my class?

I decided to try a different approach. We used bars of chocolate. This created huge enthusiasm but led to misconceptions because of the differing number of squares in each bar. I wanted to ensure that all the children, from the lowest to the highest attaining, had a real feel for and understanding of fractions.

What I did:

The focus of the lesson was the PNS framework Year 2 objective to find one half, one quarter and three quarters of shapes and sets of objects.

During the starter I used the pictures of the chocolate bars so the children experienced the idea of sharing something familiar to them. Four children were chosen to come to the front of the class, each were given a different chocolate bar to hold up. All other children had an individual whiteboard to write on.

I began by asking ‘How much do you have?’ Becky put her hand up and said ‘I have all of it!’ I then asked the rest of the class ‘Is there another way of saying all of it?’ Sam said ‘She has a whole bar!’ ;

I drew 4 bars of chocolate on w/board.

“Can someone write up under my picture how we write a whole?”

Michael wrote 1/1

I clarified that a whole can be written as 1/1 or just as 1 and wrote it up on the board as 1.

I then invited another 4 children to join the children at the front - I then asked each pair of children to tell the class how much chocolate they would have if they share equally.

Michael: "We have half a bar of chocolate each"

Nina: "We have 1 bar of chocolate but shared between 2 people"

I asked the children to draw on their board how we have shared the chocolate

Some children drew shapes like pizzas with a line down the middle, others drew a rectangle with a line down the middle

I clarified that today we are thinking about a chocolate bar shape – so it would be a rectangle rather than a circle like a pizza

“Does anyone know how we can write a half?”

I collected their ideas, some didn’t know, some wrote a one and two beside each other and some knew.

Nina: "a half is a fraction it can be written as ½"

I modelled one over two on the board. The children drew what this would look like for all the bars on their whiteboards by dividing each into two and writing the fraction ½ under each part like this:

   
1/2 1/2

Two more children were invited to join each pair at the front, so making groups of four. I asked the groups to discuss how much they each would have if they shared their bar equally and how this fraction might be written. Children with whiteboards were asked to show this visually and write the new fraction ¼ below each part. Felicity drew a rectangle cut into 4 with ¼ written below.

       
1/4  

Ben drew four lines.

I showed this as an example and asked how many parts there were, the children answered 5. How do we need to change it?

Ben answered “I have too many lines I need to take 1 away “ The children with chocolate bars then turned over their bars to show the fraction grid. I asked the children to point to which line showed one colour split into 4 parts in order to confirm with everyone what ¼ looked like and asked them to check what they had written.

Should I go further with thirds and fifths? It’s not a Year 2 objective but the children are coping well with halves and quarters?

I then asked children what would be coloured in if 2 of the 4 children put their pieces together. “Can you write the fraction to show this?”

Lisa, Tobey and Will coloured in 2/4 and wrote ½ below

Oliver drew on his board a bar split into 4 parts & labelled 2 parts as 2/4

2/4
   
   
 

Now show me what 3 people of the 4 had together

The children shaded in 3 of the 4 parts and wrote ¾. Will wrote ¼ but was able to amend his answer.

The children had practised the starter several times. As the children became more confident I introduced different fraction walls. The children then moved on to the main activity which was to use the fraction walls and model people e.g.

  • There were four people in the Brown family. They shared one bar of chocolate between them. How much chocolate did each member of the family get?
  • How much did the two children get altogether?
  • How much did all the people with blonde hair get altogether?

The children enjoyed placing the models on the fractions wall. When asked, they said they found sharing much easier to think about when they had the people/models to use because they could move the pieces around. I was pleased at their response because I did wonder whether they would be confused when we changed from the image using the chocolate bars to the practical counting. It wasn’t a problem!

Reflection:

Children were very excited by the idea of chocolate. They all wanted to be chosen as chocolate sharers. They were all engaged and participated at varying levels depending on their attainment. All children could show and write ½ and ¼ bars of chocolate. We discussed which fraction of the chocolate bar the children would most like to have ¼ or ¾ – all children recognised ¾ as being the greater amount. One child said they would prefer ¼ of the chocolate and leave the other ¾ for someone else as she didn’t like chocolate that much!

Differentiated target questions enabled me to stretch/challenge the more able pupils –with more able children recognising the lines of the wall illustrating fifths/tenths and the number of tenths that represented 1/5 and ½.

Some of the children were happily discussing eights//twelfths/sixteenths and twentieths.

How can I adapt this for older children? Could this resource be developed to build on fractions and their equivalents?

This is a flexible resource designed for you to adapt to use with your class.

We would be very grateful for your feedback. Please let us know how you used Chocolate Bar Fractions with your class and how it went in our resources community LINK to resources community.

Alternative Fraction Wall B

One Whole
1/2 1/2
1/4 1/4 1/4 1/4
1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8
1/12 1/12 1/12 1/12 1/12 1/12 1/12 1/12 1/12 1/12 1/12 1/12
 

Alternative Fraction Wall C

1/3 1/3 1/3
1/6 1/6 1/6 1/6 1/6 1/6
1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10
1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20 1/20
 
 
 
Primary
 

 


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Comments

 


09 March 2018 09:12
juliephipps - thanks for getting in touch. We've updated the resource: the first side is of a chocolate bar with ten squares, and the first number wall illustrates this. Other chocolate bars with different numbers of squares can then be drawn on a whiteboard, for example.
08 March 2018 17:02
Where are the chocolate bar pictures to download please?
By juliephipps
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24 October 2011 08:49
Etre simple c'est tres dificile - thank you!
By NCETM49
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