# Using bar models for addition and subtraction problems

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## Lesson details

### Key learning points

1. In this lesson, we will review bar models and match bar models to word problems.

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This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

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## Worksheet

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## Starter quiz

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### 5 Questions

Q1.
What can mass and capacity be measured in?
Correct answer: Mass can be measured in grams and kilograms. Capacity can be measured in millilitres and litres.
Mass can be measured in millilitres and grams. Capacity can be measured in litres and kilograms.
Mass can be measured in millilitres and litres. Capacity can be measured in grams and kilograms.
Q2.
What is the mass of the ice-cream tub?
1kg
900kg
90g
Q3.
What is the capacity of the container? (Each interval = 25ml)
650ml
700ml
725ml
Q4.
Estimate the mass of the laptop.
I know the mass weighs 1g. The laptop feels four times as heavy as the weight so I estimate the mass of the laptop is 4000g
Correct answer: I know the mass weighs 1kg. The laptop feels four times as heavy as the weight so I estimate the mass of the laptop is 4000g
I know the mass weighs 1kg. The laptop feels four times as heavy as the weight so I estimate the mass of the laptop is 4000kg
I know the mass weighs 1kg. The laptop feels four times as heavy as the weight so I estimate the mass of the laptop is 400g
Q5.
Estimate the capacity of the wheelie bin.
I know the capacity of the water bottle is 10L. The wheelie bin looks 6 times larger than the bottle so I estimate the capacity of the wheelie bin is 600L
Correct answer: I know the capacity of the water bottle is 10L. The wheelie bin looks 6 times larger than the bottle so I estimate the capacity of the wheelie bin is 60L
I know the capacity of the water bottle is 10L. The wheelie bin looks 6 times larger than the bottle so I estimate the capacity of the wheelie bin is 60ml
I know the capacity of the water bottle is 10ml. The wheelie bin looks 6 times larger than the bottle so I estimate the capacity of the wheelie bin is 60ml

## Exit quiz

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### 4 Questions

Q1.
Bar models are used for...
Correct answer: All of the above
Can be a representation of a word problem that helps to identify the calculation needed to solve it.
Help show the relationship between the known and unknown values in a problem.
Help to identify if there is a comparison between two or more values or if there are part-whole relationships or scaling relationships between values.
Q2.
What are the known and unknown values?
Known values: 89g and 35g. Unknown: The known values added together. (89g + 35g)
Known values: 89g. Unknown value: 35g
Correct answer: Known values: 89kg and 35kg. Unknown: The difference between the known values. (89g - 35g)]
Q3.
Match the word problem to the correct bar model.