Choose the most efficient strategy to subtract from a 3-digit number
Lesson details
Learning outcome
I can choose the most efficient strategy to subtract from a 3-digit number.
Key learning points
- By looking carefully at the minuend and subtrahend, we can choose the most efficient subtraction strategy.
- When numbers are close together, finding the difference is the most efficient strategy.
- Sometimes, we can use known addition facts to make finding the difference even more efficient.
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.
Partition - Partition is the act of splitting an object or value down into smaller parts.
Common misconception
Children will often reverse the minuend and subtrahend because they don't always appear in the order that they would in an expression.
Ensure that the children spend time understanding the context, either through discussion of the problem or through visual representations such as bar models. It's also worth spending time on vocabulary by playing fun word games or charades.
Teacher tip
Pupils will not always agree with the most efficient strategy selected on these slides. Efficiency is about speed and accuracy. Pupil's speed will develop with the strategy they feel most confident about. This is about mental subtraction so wherever possible get the children to do it in their heads.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is the missing whole in this bar model?
Q2.Complete the missing word minuend − subtrahend = __________
Q3.Use a find the difference strategy to calculate: 72 − 65 =
Q4.What is the difference between the two values shown?
Q5.Use a partitioning strategy to calculate 690 − 270 =
Q6.Which of the pairs of numbers have the smallest difference?
Assessment exit quiz
6 Questions
Q1.What is the equation being shown here?
Q2.Which strategy is being shown in this number line? Partitioning or counting on / back to find difference
Q3.Use an efficient strategy to calculate the missing part in the bar model.
Q4.Use an efficient strategy to solve this problem: There are 330 children in the school. 270 of the children go on a school trip to the zoo.
How many children do not go on the trip? children
Q5.Use an efficient strategy to solve this problem: Lucas has read 168 pages of his book. Alex has read 57 pages. How many more pages has Lucas read? pages
Q6.Use an efficient strategy to solve this problem: Alex and Jacob each collect football cards. Alex has 135 and Jacob has 82 cards. How many more cards does Alex have? cards
To help you plan your 3 maths lesson on: Choose the most efficient strategy to subtract from a 3-digit number, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 3 maths lesson on: Choose the most efficient strategy to subtract from a 3-digit number, 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 Informal and mental strategies for adding and subtracting two 3-digit numbers unit, dive into the full primary maths curriculum, or learn more about lesson planning.