New
New
Year 1

Furthering understanding of subtraction as decreasing an amount

I can compare subtraction as decreasing an amount to other addition and subtraction structures.

New
New
Year 1

Furthering understanding of subtraction as decreasing an amount

I can compare subtraction as decreasing an amount to other addition and subtraction structures.

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Lesson details

Key learning points

  1. Subtraction can be seen as both partitioning and as decreasing an amount.
  2. Both types of subtraction stories are represented by the same equation.
  3. In an addition story, the amount at the start of the story is increased.
  4. In an subtraction story, the amount at the start of the story is decreased.

Common misconception

After exploring reduction, children may struggle to see partitioning as subtraction because a part is not taken away from the whole.

Make strong links between equations and different subtraction contexts by focusing on what the subtrahend represents in each case.

Keywords

  • Subtraction - To partition one part from another (the subtrahend from the difference), or to decrease an amount by taking an amount away.

  • Decrease - Make something smaller in size or quantity decrease.

  • Addition - To find the total, or sum, by combining two or more parts (addends), or to increase an amount by adding another.

  • Increase - To make something larger/greater in size or quantity.

Encourage children to explain how each subtraction story is represented as an equation, articulating what each part of the equation represents. The inverse relationship between addition and subtraction will be focused upon in depth in a later lesson.
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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6 Questions

Q1.
6 - 2 = 4 First, there were 6 apples on the plate. Then, 2 apples were taken off the plate. Now, there are 4 apples on the plate. What does the 2 represent in this story?
The amount left at the end of the story
The amount at the start of the story
Correct answer: The amount subtracted
Q2.
Which story could match this picture?
An image in a quiz
Correct answer: First, there were 5 birds. Then, 1 flew off. Now, there are 4 birds.
First, there were 5 birds. Then, 4 flew off. Now, there are 4 birds.
First, there were 4 birds. Then, one flew in. Now, there are 5 birds.
Q3.
Which equation matches this story?
An image in a quiz
8 - 5 = 3
5 + 3 = 8
Correct answer: 8 - 3 = 5
Q4.
Which equation matches the story?
An image in a quiz
7 - 3 = 4
Correct answer: 7 - 4 = 3
3 + 4 = 7
Q5.
What is the subtrahend in this problem?
An image in a quiz
Correct answer: 3
4
5
Q6.
Match the story to the equation it represents.
Correct Answer:8 - 4 = 4,First, there were 8 cars. Then, 4 drove away. Now, there are 4 cars.

First, there were 8 cars. Then, 4 drove away. Now, there are 4 cars.

Correct Answer:5 - 5 = 0,First, there were 5 dogs. Then, 5 ran away. Now, there are 0 dogs.

First, there were 5 dogs. Then, 5 ran away. Now, there are 0 dogs.

Correct Answer:10 - 6 = 4,First, there were 10 birds. Then, 6 flew away. Now, there are 4 birds.

First, there were 10 birds. Then, 6 flew away. Now, there are 4 birds.

6 Questions

Q1.
A monkey has 7 bananas. She eats 5 of them. How many bananas does she have left?
4
Correct answer: 2
7
Q2.
Which equation matches this 'First, then, now' story?
An image in a quiz
Correct answer: 6 - 5 = 1
6 - 4 = 2
6 - 1 = 5
Q3.
Write an equation to represent this story.
An image in a quiz
Correct Answer: 8 - 3 = 5, 8-3=5
Q4.
Is this number line showing an increase or a decrease from the amount at the start of the story?
An image in a quiz
Correct answer: Increase
Decrease
Q5.
Is this story showing an increase or a decrease from the first amount?
An image in a quiz
Correct answer: Increase
Decrease
Q6.
Which of these stories is correct?
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz