Introduction to Fractions

Key concept

Fractions show part of a whole split into equal parts, like a pizza cut into 9 equal slices where taking 4 gives 4/9. The numerator (4) counts the parts taken; the denominator (9) counts the total equal parts.

Introduction to Fractions - introduction visual

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Introduction to Fractions poster

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Flashcards

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Explanation of fractions with a pizza divided into eight slices, illustrating one-eighth and three-eighths fractions.Explanation of fractions with numerators and denominators, showing a pizza divided into eight equal parts.Understanding fractions with examples, showing 4 out of 9 coloured parts in a circle and an unequally divided rectangle.Applying fractions to real-world examples, including finding 3/4 of 20 cm using a ruler and 5/6 of 2 hours using a clock.Splitting £50 using fractions: the calculation shows it is divided into 10 parts, 1 part = £5, your share = 3 parts, total = £15.

What is a Fraction?

  • A fraction shows part of a whole.
  • For example, if a pizza is cut into 8 equal slices and you take 3, the fraction is 3/8.

Parts of a Fraction (Example: 3/8)

  • The numerator (3) shows how many parts are taken.
  • The denominator (8) shows how many equal parts the whole is split into.

Exam Rule: Equal Parts

  • Fractions only work when the whole is divided into equal parts.
  • If the parts are not equal, you cannot write a correct fraction.

How Do You Find a Fraction of an Amount?

  • Divide the total by the denominator to find one part: .
  • Multiply that by the numerator to get the answer: .
  • So, 3/4 of .

Finding Missing Fractions

  • The parts of a whole must add up to 1.
  • To find a missing fraction, subtract the known fractions from 1.

Practice Questions

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Q1Easy

In a fraction, what does the denominator tell us?

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Interactive Activity

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Frequently asked questions

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A fraction is a part of a whole split into equal parts. Cut a pizza into 8 equal slices and eat 3, and you have eaten 3/8 of it. Equal is the key word: if a shape is cut into unequal pieces, you cannot write a fraction for it. When the top and bottom numbers match, as in 8/8, the fraction is one whole.

The denominator is the bottom number: it says how many equal parts the whole is divided into. The numerator is the top number: it says how many of those parts you are counting. In 4/9, a circle cut into 9 equal parts with 4 coloured in, the denominator is 9 and the numerator is 4. A horizontal bar separates them.

Divide the amount by the denominator to find one part, then multiply by the numerator. For 3/4 of 20 cm: 20 ÷ 4 = 5 cm, and 3 × 5 = 15 cm. If the amount does not divide easily, change the units first: 5/6 of 2 hours is 5/6 of 120 minutes, so 120 ÷ 6 = 20 and 5 × 20 = 100 minutes.

The parts of a whole add up to 1, so subtract the fractions you know from 1. Three friends share a £50 gift: Emma pays 4/10 and Alex 3/10, so 4/10 + 3/10 = 7/10 is covered and 3/10 is left for you. Each tenth of £50 is £5, so your share is 3 × £5 = £15.

Use food. Cut a pizza into equal slices and count them: that number goes on the bottom. Take some slices and count those: that goes on top. Three slices of eight is 3/8. Then ask what happens if the slices are different sizes, and your child will see why the parts must be equal.

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