Add and subtract mentally without bridging a boundary
Lesson details
Learning outcome
I can add and subtract mentally without bridging a boundary with one or more digits changing
Key learning points
- Known facts to 10 can be applied when adding and subtracting 100s, 1,000s, 10,000s and 100,000s
- When adding and subtracting mentally, the language of unitising supports us in addition to using known facts.
- An understanding of the structure of numbers and place value supports when we add and subtract mentally.
Keywords
Addend - An addend is a number added to another. They are also known as the parts.
Common misconception
Children may believe that only one digit will change when adding two numbers where one addend has only one non-zero digit.
This is usually correct but what would happen if the digit changed to a value of 10 or greater? Then we would need to regroup (another lesson).
Teacher tip
The lesson should be as practical as possible, using place value counters and charts to support children to see the digits that change/s.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Complete: is 3,000 more than 6,000
Q2.1,306 + 400 =
Q3.Two plus three is equal to five so two thousand plus three thousand is equal to ___
Q4. is forty thousand less than ninety thousand. Give your answer as a numeral using digits.
Q5.6,709 − 3,000 = ___
Q6.Lucas thinks of a number. His number is 5,100 more than 13,215 What is his number?
Assessment exit quiz
6 Questions
Q1.3,901,481 + 3,000 = ___
Q2.Complete: 8,940,305 − 300,000 =
Q3.Match the addends to their sum.
Q4.7,154,302 + 500,000 − 400,000 =
Q5.Match the equations to their difference.
Q6.Lucas thinks of a number. His number is 561,000 less than 3,994,314 What number is Lucas thinking of?
To help you plan your 6 maths lesson on: Add and subtract mentally without bridging a boundary, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 6 maths lesson on: Add and subtract mentally without bridging a boundary, 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 Order, compare and calculate with numbers up to 8 digits unit, dive into the full primary maths curriculum, or learn more about lesson planning.