New
New
Year 3

# Solve problems involving length and height

I can solve problems about lengths and heights.

New
New
Year 3

# Solve problems involving length and height

I can solve problems about lengths and heights.

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## Lesson details

### Key learning points

1. Word problems can be represented in a bar model by identifying the parts and the whole.
2. To find the whole, we need to add the parts together.
3. To find a part, we need to subtract the part we know from the whole.
4. If the units are different, they need to be converted to the same unit.

### Common misconception

Converting between units; interpreting a word problem; confusing parts and wholes.

When representing as a bar model, visualise the problem to help determine what the parts are and what the whole is.

### Keywords

• Bar model - A pictorial representation of a problem where bars are used to represent the known and unknown quantities.

• Part - Some but not all of something. It is an amount or section which, when combined with others, makes up the whole.

• Whole - All of something. It is complete.

Really focus on getting children to visualise the problem in a real life context. Use concrete resources where possible. Focus on the key words that cause confusion eg. 'how much more', which is finding the difference even though it uses 'more'.
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).

## Starter quiz

### 6 Questions

Q1.
A standardised unit of measure that is equivalent in length to 100 cm is called a .
millimetre
gram
kilogram
Q2.
Match the calculation to its answer.
Correct Answer:100 - 60 =,40

40

Correct Answer:100 - 40 =,60

60

Correct Answer:110 + 50 = ,160

160

Correct Answer:30 + 20 + 50 =,100

100

Q3.
Match the equivalent measures.
Correct Answer:1 m 1 cm ,101 cm

101 cm

Correct Answer:1 m 10 cm,110 cm

110 cm

Correct Answer:11 cm,110 mm

110 mm

Correct Answer:2 m,200 cm

200 cm

Q4.
Match the calculation to its answer.
Correct Answer:30 cm - 80 mm =,50 cm

50 cm

Correct Answer:1 m - 20 cm =,80 cm

80 cm

Correct Answer:2 m - 1 m =,100 cm

100 cm

Correct Answer:2 m - 50 cm =,150 cm

150 cm

Q5.
Starting with the shortest, put these lengths in order.
1 - 9 mm
2 - 1 cm
3 - 11 mm
4 - 1 cm 2 mm
6 - 2 cm 1 mm
Q6.
Look at this bar model. Find the missing part.
490
210

## Exit quiz

### 6 Questions

Q1.
Look at this word problem and empty bar model. Match the given lengths to the whole or a part.
Correct Answer:2 m,The whole.

The whole.

Correct Answer:40 cm,A part.

A part.

Q2.
Use the bar model to support you to identify the calculation, and then solve the problem. Choose two correct answers.
1 m 40 cm
140 cm
Correct answer: 2 m 60 cm
Correct answer: 260 cm
Q3.
Use the bar model to support you to identify the calculation, and then solve the problem.
5 m 10 cm
90 m
213 cm
Correct answer: 90 cm
Q4.
Izzy's sunflower is 3 m 90 cm tall. Andeep's is 200 cm tall. How much taller is Izzy's sunflower than Andeep's? Choose all possible options.
590 cm
Correct answer: 1 m 90 cm
Correct answer: 190 cm
3 m 290 cm
Q5.
Use the bar model to support you to identify the calculation, and then solve the problem. Choose all possible options.
13 m
Correct answer: 1 m
298 cm
Correct answer: 100 cm
Q6.
Izzy lays two sticks end to end. The first stick is 20 cm long. The second stick is 40 mm long. Jacob has a stick that is 50 cm long. How much longer is Jacob's stick than the total length of Izzy's?
110 cm
74 cm
36 cm
Correct answer: 26 cm