New
New
Year 5

Compare and describe lengths using knowledge of division

I can compare and describe lengths using knowledge of division.

New
New
Year 5

Compare and describe lengths using knowledge of division

I can compare and describe lengths using knowledge of division.

Lesson details

Key learning points

  1. Lengths can be compared using division.
  2. The stem sentence, 'The ___ is ___ times the length of the ___' can be used to compare and describe lengths.
  3. Comparisons of length can be represented as multiplication equations with a fractional multiplier.

Keywords

  • Times the length/height/depth - Times the length/height/depth is a phrase that is used to compare and describe lengths or heights. For example, one tree might be three times the height of another tree; it is three times as tall.

  • Unit fraction - A unit fraction is a fraction where the numerator is one.

Common misconception

Children are more familiar with multiplication resulting in an increase and so may not accept that it can also result in a decrease.

When we multiply by a unit fraction, it is the same as dividing the whole by the denominator. This results in a decrease in length.

Note that typically we would say ‘the spotty ribbon is one-third the length of the plain ribbon’. However, '... is one-third times the length ...' should be used to draw attention to the structure and to link to the multiplication equation. Practical experiences should be offered where possible.
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).

Lesson video

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6 Questions

Q1.
A piece of elastic stretches to 3 times its original length. Which bar model represents this?
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q2.
The original piece of elastic was 50 cm long. How long is it now it has stretched to three times it's original length?
50 cm
100 cm
Correct answer: 150 cm
53 cm
Q3.
Hamish the cat is 4 times as tall as a mouse. If the mouse is 8 cm tall, how tall is the cat? The cat is cm tall.
An image in a quiz
Correct Answer: 32, 32cm, thirty two
Q4.
How many 20s are there in 140?
Correct Answer: 7, seven, Seven
Q5.
45 is 15 times the size of
Correct Answer: 3, three, Three
Q6.
What number is ten times the size of 12?
102
22
112
Correct answer: 120

6 Questions

Q1.
Which image represents this statement? The green ribbon is one-half times the length of the white ribbon.
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q2.
If the white ribbon is 14 cm long, how long is the green ribbon if it is one-half times the length?
An image in a quiz
16
12
28
Correct answer: 7
Q3.
Which equations show that one half of 14 cm is equal to 7 cm?
Correct answer: 14 ÷ 2 = 7
7 ÷ 2 = 14
Correct answer: 14 × $${1}\over{2}$$ = 7
7 × $${1}\over{2}$$ = 14
Q4.
Lucas has spent half of his money. He has £13 left. How much money did he have to start with?
£6.50
Correct answer: £26
Q5.
The white ribbon is the whole. Which sentence describes the length of the shorter red ribbon?
An image in a quiz
The red ribbon is one half the length of the white ribbon.
The red ribbon is the same length as the white ribbon.
Correct answer: The red ribbon is one third the length of the white ribbon.
Q6.
The red ribbon is one third times the length of the white ribbon. If the white ribbon is 60 cm long, how long is the red ribbon?
An image in a quiz
180 cm
120 cm
30 cm
Correct answer: 20 cm