Understand subtraction as decreasing an amount
Lesson details
Learning outcome
I can describe and interpret subtraction stories which involve decreasing an amount and write equations to represent this.
Key learning points
- Decreasing the first amount in a story is a type of subtraction.
- It can be represented as a ‘First, then, now’ story.
- It can also be represented as an equation.
- The first amount in a ‘First, then, now’ story must be written first in an equation.
Keywords
First - Before anything else.
Then - After something in time.
Now - At the present time.
Decrease - Make something smaller in size or quantity.
Common misconception
Children may find the ‘then’ part of the story, where the amount changes, difficult to identify.
Draw attention to the change, talking about it as a decrease.
Teacher tip
Draw attention to how the reduction structure of subtraction is different to partitioning. Use 'take away' interchangeably with 'subtract' here to help highlight that the subtrahend is physically taken away rather than just 'partitioned' from the difference.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Write a subtraction equation that could represent the counters.
Q2.What subtraction equation could represent this story?
There were 5 children altogether in the whole group.
1 had brown hair.
How many did not have brown hair?
Q3.Alex writes this addition equation to represent the bar model.
2 + 7 = 9
Which subtraction equation could also be represented by the bar model?
Q4.Which set of counters could represent this story?
There were 6 teddies altogether in the whole group.
4 were small teddies.
How many were not small teddies?
Q5.Tick the subtraction equations which could be represented by this bar model.
Q6.Which of these is a subtraction story?
Assessment exit quiz
6 Questions
Q1.Alex writes an equation to match his story.
7 - 2 = 5
What does the 5 represent?
Q2.Which story could match this picture?
Q3.Which set of counters would represent this story?
First, there were 10 pounds in my pocket.
Then, I spent 4 pounds.
Now, there are 6 pounds in my pocket.
Q4.Which equation matches the picture?
Q5.Which equation matches the story?
Q6.Write an equation to match the picture.
To help you plan your 1 maths lesson on: Understand subtraction as decreasing an amount, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 1 maths lesson on: Understand subtraction as decreasing an amount, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 1 maths lessons from the Additive structures: addition and subtraction unit, dive into the full primary maths curriculum, or learn more about lesson planning.