Unit Fractions: One Equal Part

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What this lesson covers

  • A fraction can be part of a shape, part of a set, part of a length, or a point on a number line.
  • A unit fraction is one of the equal parts. Its top number is 1.
  • The bottom number says how many equal parts make the whole.
  • The bigger the bottom number, the smaller the unit fraction.
Key idea

Equal parts

  • A fraction is part of a whole that has been cut into equal parts.
  • 1/4 means 1 of 4 equal parts. Say it: one quarter.
  • The top number (numerator) counts the parts. The bottom number (denominator) says how many equal parts there are.
  • If the parts are not equal, they are not quarters.
Worked example

Unit fractions and their names

  • A unit fraction has 1 on top.
FractionSay itEqual parts in the whole
1/2one half2
1/3one third3
1/4one quarter4
1/5one fifth5
1/6one sixth6
1/8one eighth8
1/10one tenth10
Worked example

Fractions everywhere

  • Each one is equal parts of a whole.
Fraction ofExample
a shapeCut a sandwich into 4 equal pieces. One piece is 1/4.
a setA box of 6 eggs. 1/3 of the eggs is 2 eggs.
a length1/2 of a metre is 50 cm.
a number lineCut 0 to 1 into 4 equal jumps. The first mark is 1/4.
Key idea

Try it: a fraction on the number line

Key idea

Counting in unit fractions

  • Count in quarters: 1/4, 2/4, 3/4, 4/4.
  • 4/4 is all four quarters: one whole.
  • Count in thirds: 1/3, 2/3, 3/3. 3/3 is one whole.
Key idea

More parts, smaller pieces

  • Share a cake between 2 people and each gets 1/2.
  • Share it between 12 people and each gets 1/12. Much smaller.
  • The bigger the bottom number, the smaller the piece.
  • So 1/12 < 1/6 < 1/3 < 1/2.
Key idea

Try it: the fraction wall

Common mistakes

  • 1/8 is bigger than 1/4 because 8 is bigger than 4.
    Eighths are smaller pieces than quarters, so 1/8 is smaller than 1/4.
  • A shape cut into 4 pieces of any size shows quarters.
    Quarters must be 4 equal parts.
  • 1/3 of 6 eggs is 3 eggs.
    Split 6 eggs into 3 equal groups. Each group has 2 eggs.
  • 4/4 is more than one whole.
    4/4 is all 4 quarters, which is exactly one whole.

Your turn

1

A pizza is cut into 8 equal slices. What fraction is one slice?

2

Which is the biggest: 1/5, 1/10, 1/3 or 1/8?

3

What is 1/2 of 10 apples?

4

Count in thirds: 1/3, 2/3, __

5

Put 1/2, 1/12 and 1/4 in order from smallest to largest.

Show answer

1. 1/8 2. 1/3 3. 5 apples 4. 3/3, which is one whole 5. 1/12, 1/4, 1/2

Summary

What to take away

  • Fractions are equal parts.
  • A unit fraction is one part, with 1 on top.
  • More parts means smaller parts.
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More in Number

Numbers to 1,000: Hundreds, Tens and OnesNotesCounting in Groups, Rounding and EstimatingNotesSkip Counting, Odd and Even NumbersNotesAdding and Subtracting up to 1,000NotesMultiplying and Dividing with GroupsNotesUnit Fractions: One Equal PartNotesComparing Fractions and Finding Equal OnesNotesAdding Fractions and Finding Fractions of NumbersNotesDollars, Cents and Giving ChangeNotes

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