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Butterfly Method Fractions

Butterfly Method Fractions

As a primary teacher, you’ll probably have taught several different methods for adding and subtracting fractions, but have you ever tried butterfly method fractions? This simple, visual method might just be worth a try with your KS2 class. 

How do Butterfly Method Fractions work? 

Start by writing out your calculation: 

Two fifths plus three quarters

Now draw two butterfly wings by drawing two diagonal ovals: 

Diagonal ovals around the right numerator and left denominator, and vice versa

Now draw two antennae, like this: 

Two antennas coming out of the top two wings

Multiply the numbers in the first oval and record the product: 

Two multiplied by four equals eight. This is written by the first antenna.

Now do the same in the second oval: 

Three multipled by 5 is 15. This is written by the second antenna.

Give the butterfly a tail and multiply the two bottom wings together: 

Five multiplied by four is 20. This is written under the tail.

This bottom number will now be your denominator…

Twenty is written as the denominator in the answer

...and you can add the two antennae numbers to make the numerator: 

Eight plus fifteen is 23. This is written as the numerator in the answer.

You can then convert or simplify your answer. 

Twenty-three twentieths is the same as one and three twentieths

And there you have it! Butterfly Method Fractions. Easy, right?! 

How do you use Butterfly Method Fractions to subtract fractions? 

All you need to do differently is to subtract the smaller number from the antenna from the larger number. 

Method shown for subtracting fractions

Why not try using the butterfly method for adding and subtracting fractions with your class and see how they get on? As an added challenge, ask them to explain in their own words how the method works. 

You can find Butterfly Method Fractions within our Calculating Decimals and Fractions Maths lessons for Year 6. Why not check out our fully-prepared library of primary Maths lessons? 


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