Solve problems involving subtraction of two-digit numbers
Lesson details
Learning outcome
I can solve problems involving subtraction of two-digit numbers that do not cross the tens boundary.
Key learning points
- When subtracting a 2-digit number, the known part can be partitioned to subtract the tens and the ones separately.
- Partitioning both the whole and the parts when subtracting gives an correct answer when the ones digits bridge 10
- The tens and ones can be subtracted in any order and the remaining part will stay the same.
Keywords
Partition - To split a whole up into parts - a piece or section of a whole.
Part - A piece or section of a whole.
Common misconception
Children may think that, when partitioned, the tens and ones must be subtracted in the same order as they occur in the two-digit number, e.g. that to subtract 34, you must subtract 30, then 4
Explore subtracting tens and ones in any order at this point, looking at the result of this and considering which they find easier.
Teacher tip
Although we encourage children to choose to subtract in any order to work efficiently here, it is important that they realise when decreasing an amount, the order can be important to the story - this understanding will support when solving two-step problems in the future.
Licence
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.Match the expressions that have the same value.
65 − 32
74 − 44
26 − 13
Q2.Which number is missing in the equation? 89 − 28 = 89 − 8 −
Q3.Which equation is represented by the number line?
Q4.Find the missing part in the bar model.
Q5.How many tens are in the missing part? 95 − _2 = 23
Q6.Find the missing part. 67 − = 34
Assessment exit quiz
6 Questions
Q1.Which bar model represents the problem shown? First, there were 47 cows in the field. Then, 3 left, then 20 more left. How many cows are left in the field now?
Q2.Which number line represents what has happened in the problem? First, there were 87 sheep in the field. Then, 5 left, then 20 more left. How many cows are left in the field now?
Q3.Izzy had 56 p and spent 25 p. How much money does she have left? Use the coins shown to help you find out.
Q4.Which number line represents what has happened in the problem? I had 69 sweets in my bag. 34 were gobstoppers and the rest were bon-bons. How many were bon-bons?
Q5.Andeep counts 87 minibeasts in the garden. 35 were ants and the rest were woodlice. How many woodlice were there? Which equation would solve this problem?
Q6.There are 86 crows on the farmer’s field and 53 fly away. How many crows are left? Write the equation to solve this problem.
To help you plan your 2 maths lesson on: Solve problems involving subtraction of two-digit numbers, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 2 maths lesson on: Solve problems involving subtraction of two-digit numbers, 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 Addition and subtraction of two 2-digit numbers unit, dive into the full primary maths curriculum, or learn more about lesson planning.