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Year 7

Ordering fractions by way of a common denominator

I can compare and order fractions by converting to fractions with a common denominator.

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Share activities with pupils
New
New
Year 7

Ordering fractions by way of a common denominator

I can compare and order fractions by converting to fractions with a common denominator.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. When a fraction is multiplied by 1 it remains the same but may look different.
  2. Two fractions can be written with the same denominator by using the lowest common multiple.
  3. Two fractions can be compared when they have the same denominator.
  4. A list of fractions can be ordered by writing them all as equivalent fractions with the same denominator.

Common misconception

Choosing to the find the product of the denominators in order to compare fractions.

Although this is not wrong it can be inefficient. This can be illustrated using large denominators which have a much lower HCF.

Keywords

  • Numerator - The expression in a fraction that is written above the fraction line. It is the dividend.

  • Denominator - The expression in a fraction that is written below the fraction line. It is the divisor.

  • Lowest common multiple - The lowest common multiple is the lowest number that is a multiple of two or more numbers.

Devise a classroom friendly competition but allow each chosen pupil a different number of trials. This should lead to a discussion about who did the best and feed into the idea of converting so they all have a common denominator.
Teacher tip

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).

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Starter quiz

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6 Questions

Q1.
The numerator is the expression in a fraction that is written above the fraction line. It is the .
Correct Answer: dividend
Q2.
The denominator is the expression in a fraction that is written below the fraction line. It is the .
Correct Answer: divisor
Q3.
Order the steps to show how to convert $$\frac{9}{8}$$ to a decimal
1 - $$\frac{9}{8} \times 1$$
2 - $$\frac{9}{8} \times \frac{125}{125}$$
3 - $$\frac{9 \times 125}{8 \times 125}$$
4 - $$\frac{1125}{1000}$$
5 - $$1.125$$
Q4.
In order to compare fractions, you must always convert them to have the same denominator.
True
Correct answer: False
Q5.
Order these values from smallest to largest.
1 - $$9.45$$
2 - $$9\frac{5}{8}$$
3 - $$9\frac{3}{4}$$
4 - $$9.92$$
Q6.
Order these values from smallest to largest.
1 - $$\frac{17}{20}$$
2 - $$0.875$$
3 - $$0.92$$
4 - $$\frac{15}{16}$$

Exit quiz

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6 Questions

Q1.
Order the steps to show that $$\frac{7}{8}$$ is not equivalent to $$\frac{42}{56}$$
1 - $$\frac{7}{8} \times 1$$
2 - $$\frac{7}{8} \times \frac{7}{7}$$
3 - $$\frac{7 \times 7}{8 \times 7}$$
4 - $$\frac{49}{56}$$
Q2.
True or false? $$\frac{12}{13} = \frac{72}{78}$$
Correct answer: True
False
Q3.
Which of the following are true?
Correct answer: $$\frac{2}{3} = \frac{32}{48}$$
$$\frac{4}{9} = \frac{20}{36}$$
Correct answer: $$\frac{7}{8} = \frac{63}{72}$$
Correct answer: $$\frac{48}{144} = \frac{1}{3}$$
$$\frac{119}{80} = \frac{7}{5}$$
Q4.
Select the correct symbol to make the statement true. $$\frac{3}{8}\ \square \ \frac{9}{24} $$
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>
Correct answer: =
Q5.
Select the correct symbol to make the statement true. $$\frac{5}{21}\ \square \ \frac{6}{14} $$
Correct answer: <
>
=
Q6.
Select the correct symbol to make the statement true. $$\frac{7}{12}\ \square \ \frac{9}{16} $$
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Correct answer: >
=