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

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

Inverse means the opposite in effect; the reverse of.

Represent the inverse relationship between addition and subtraction

Maths

In this unit pupils will find missing addends in equations. They will partition a whole into 2 parts representing first, then, now stories with subtraction equations. They will learn + and - are inverse operations. In the future unit pupils will explain that addition is commutative. They will find pairs of numbers to 10 and add or subtract 1 from any number.

In prior learning, pupils will have learnt to count confidently and have developed a deep understanding of the numbers to 10, the relationships between them and the patterns within those numbers. In this unit pupils will find missing addends. They will partition a whole into two parts and represent it with subtraction equations learning that addition and subtraction are inverse operations.

Additive structures: addition and subtraction

Aisha picks up 4 beads. 
First, she picks up 3 white beads. Then, she picks up 1 red bead. 
She represents this with this equation 3 + 1 = 4
What subtraction equation would she write to undo this?

What amount will make this representation correct? What number is missing from the number line?

Alex collects some conkers.
First, he puts 6 conkers in his pocket but then 5 conkers fall out. Now, he has 1 left. 
6 − 5 = 1
Which equation would undo this change?

Which pair of equations are being shown in this picture?

Aisha says, "First I had 3 cubes. Then Alex gave me 6 more. Now I have 9 cubes."

Alex says, "First I had 9 cubes. Then I gave 6 to Aisha. Now I have 3 cubes."

Aisha and Alex are telling their own 'First, then, now' stories for this picture. Who is correct?

I created a picture to show a 'First, then, so, then, now' story.
How much was added to the amount at the start of the story?

This picture has been represented with the equation 2 + 5 = 7
Which number must be subtracted to undo the change?

Match the addition equations to the inverse equation.

First, there were 8 cakes on my plate. Then, 3 cakes were eaten. Now, there are 5 cakes on my plate. 
Write the equation which would undo the change made in this story?

Look at the picture. Which of the following represents the story?

Which equation would undo the addition 5 + 1 = 6

Which equation would undo the subtraction 9 − 5 = 4

This lesson will soon be taken down.

Represent the inverse relationship between addition and subtraction

Lesson outcome