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Year 3

Subtract fractions from a whole by converting the whole to a fraction

I can subtract fractions from a whole by converting the whole to a fraction.

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Share activities with pupils
New
New
Year 3

Subtract fractions from a whole by converting the whole to a fraction

I can subtract fractions from a whole by converting the whole to a fraction.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. A fraction with the same numerator and denominator is equal to one whole.
  2. To subtract a fraction from a whole, convert the whole to a fraction with the same denominator as the subtrahend.
  3. The minuend and subtrahend have the same denominator to subtract easily.
  4. When the denominators are the same, you subtract the numerators using the language of unitising.

Common misconception

Children often find it difficult to understand the idea that any whole can be represented by a fraction with the same numerator and denominator.

You might want to list down some different real life examples such as slices of pizza or pie, complete sets of sticker pages, full packs of pens/pencils. Label each example with fraction notation so the children get a firmer understanding.

Keywords

  • Minuend - The minuend is the number being subtracted from.

  • Subtrahend - A subtrahend is a number subtracted from another. There can be more than one.

  • Numerator - A numerator is the top number in a fraction. It shows how many parts we have.

  • Denominator - A denominator is the bottom number in a fraction. It shows how many parts a whole has been divided into.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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Starter quiz

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6 Questions

Q1.
What is the missing fraction in this bar model?
An image in a quiz
Correct answer: $$ \frac{2}{10} $$
$$ \frac{3}{10} $$
$$ \frac{16}{10} $$
Q2.
Which equation is shown on the number line?
An image in a quiz
$$ \frac{9}{10} $$ − $$ \frac{3}{10} $$ = $$ \frac{6}{10} $$
Correct answer: $$ \frac{9}{10} $$ − $$ \frac{6}{10} $$ = $$ \frac{3}{10} $$
$$ \frac{3}{10} $$ + $$ \frac{9}{10} $$ = $$ \frac{9}{10} $$
Q3.
Aisha and Alex share a pizza cut into 8 slices. Alex eats five-eighths of the pizza. How much does Aisha eat? Aisha eats ___ of the pizza.
An image in a quiz
Correct answer: $$ \frac{3}{8} $$
$$ \frac{5}{8} $$
$$ \frac{5}{16} $$
$$ \frac{5}{5} $$
Q4.
A full box of eggs contains 12 eggs. First there were 8 eggs in the box, then 5 were used to make pancakes. Which equation matches this problem?
An image in a quiz
$$ \frac{8}{12} $$ − $$ \frac{5}{12} $$ = $$ \frac{13}{12} $$
Correct answer: $$ \frac{8}{12} $$ − $$ \frac{5}{12} $$ = $$ \frac{3}{12} $$
$$ \frac{8}{12} $$ − $$ \frac{5}{12} $$ = $$ \frac{3}{0} $$
$$ \frac{8}{12} $$ − $$ \frac{5}{12} $$ = $$ \frac{3}{24} $$
Q5.
Which equation is the inverse of $$ \frac{3}{8} $$ + $$ \frac{4}{8} $$ = $$ \frac{7}{8} $$?
Correct answer: $$ \frac{7}{8} $$ − $$ \frac{4}{8} $$ = $$ \frac{3}{8} $$
$$ \frac{3}{8} $$ − $$ \frac{4}{8} $$ = $$ \frac{7}{8} $$
$$ \frac{7}{8} $$ + $$ \frac{3}{8} $$ = $$ \frac{4}{8} $$
Q6.
Which of the additive equations are correct for this bar model?
An image in a quiz
Correct answer: $$ \frac{12}{15} $$ − $$ \frac{9}{15} $$ = $$ \frac{3}{15} $$
$$ \frac{9}{15} $$ − $$ \frac{3}{15} $$ = $$ \frac{12}{15} $$
Correct answer: $$ \frac{9}{15} $$ + $$ \frac{3}{15} $$ = $$ \frac{12}{15} $$
Correct answer: $$ \frac{3}{15} $$ + $$ \frac{9}{15} $$ = $$ \frac{12}{15} $$

Exit quiz

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6 Questions

Q1.
When the numerator and denominator are the same, the fraction is __________ one whole.
less than
Correct answer: equal to
greater than
Q2.
Match the number of fractional parts to the whole.
Correct Answer:5,is the number of fifths equal to one whole.

is the number of fifths equal to one whole.

Correct Answer:10,is the number of tenths equal to one whole.

is the number of tenths equal to one whole.

Correct Answer:3, is the number of thirds equal to one whole.

is the number of thirds equal to one whole.

Correct Answer:4,is the number of quarters equal to one whole.

is the number of quarters equal to one whole.

Q3.
Which of these fractions are equivalent to 1?
Correct answer: $$ \frac{8}{8} $$
$$ \frac{1}{2} $$
Correct answer: $$ \frac{10}{10} $$
Correct answer: $$ \frac{15}{15} $$
$$ \frac{1}{3} $$
Q4.
Sam has a full bottle of bubble mixture. She uses one-sixth of the mixture to blow some bubbles. What fraction of the bubble mixture remains?
An image in a quiz
$$ \frac{6}{6} $$
Correct answer: $$ \frac{5}{6} $$
$$ \frac{4}{6} $$
Q5.
Izzy has a multipack of 10 juice blast drinks. She drinks one on Sunday, Wednesday and Friday. What fraction of the multipack is left?
An image in a quiz
$$ \frac{6}{10} $$
Correct answer: $$ \frac{7}{10} $$
$$ \frac{8}{10} $$
Q6.
What is the missing fraction in this equation?
An image in a quiz
$$ \frac{8}{0} $$
Correct answer: $$ \frac{8}{11} $$
$$ \frac{14}{11} $$