Identify knowns and unknowns in subtraction equations
Lesson details
Learning outcome
I can identify knowns and unknowns in subtraction equations.
Key learning points
- Equations can be represented using part-part-whole or bar models.
- If the minuend is missing, you add the subtrahend and difference.
- To find a missing part in a subtraction equation, subtract the other part from the whole.
Keywords
Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another.
Difference - The difference is the result after subtracting one number from another.
Common misconception
Pupils may rely on the same strategies to solve all problems and may find it hard to remember when to add to find the missing part and when to subtract.
Emphasise the use of bar models, especially for pupils who are struggling. This will help them identify whether a part is missing or if the whole is missing, and whether they should add the parts or subtract a part from the whole to get the answer.
Teacher tip
Bar models and number lines may be useful for this session. The numbers involved should be very familiar to pupils, but they may find the concept of subtraction calculations with missing parts challenging, especially deciding when they should use addition or subtraction to find the answer.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which number represents the subtrahend in this equation? 31 − 10 = 21
Q2.What is the difference between 19 and 21?
Q3.What is 100 − 30 =
Q4.What is 200 − 50 =
Q5.Calculate the missing number is this equation: 40 + ___ = 220
Q6.Which pairs of numbers have a sum of 600?
Assessment exit quiz
6 Questions
Q1.Which number in this equation is the minuend? 63 = 103 − 40
Q2.What is the difference between 190 and 210?
Q3.Calculate the missing number in this equation: − 30 = 60
Q4.Calculate the missing number in this equation: 63 − = 20
Q5.Match up the differences with the correct expression to complete each equation.
36 − 10
66 − 20
84 − 20
44 − 10
Q6.Sylvie the snail creeps 130 cm towards home. She still has 105 cm to go before she gets there. How many cm will she have travelled altogether? cm
To help you plan your 3 maths lesson on: Identify knowns and unknowns in subtraction equations, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 3 maths lesson on: Identify knowns and unknowns in subtraction equations, 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 2 maths lessons from the Understand additive relationships and apply them to rearrange equations unit, dive into the full primary maths curriculum, or learn more about lesson planning.