Use knowledge of calculating within 20 to solve problems
Lesson details
Learning outcome
I can use knowledge of calculating within 20 to solve problems in a range of contexts.
Key learning points
- When adding three addends, it is efficient to first add two addends using a known fact e.g. pair to 10 or double.
- When adding, we can bridge 10 by partitioning a part so that we can ‘make 10’.
- When subtracting, we can bridge 10 by partitioning a part to create a part that is equal to the ones digit of whole.
- The difference can be found through subtraction.
Keywords
Visualise - To imagine a given problem before us in real life.
Represent - To communicate mathematical ideas through models.
Calculate - To choose one of the four operations to solve a problem.
Efficient - Not wasting time or effort. An efficient strategy is one we can carry out easily.
Common misconception
Without correct representation, children may struggle to know what to calculate.
If needed, provide support at this stage so that the structure of the mathematics is clear to children.
Teacher tip
This lesson recognises the crucial step in problem solving where children 'see' and 'represent' the mathematics before calculating. This gives them confidence in knowing what to do to solve the problem and minimises the chance of children jumping to conclusion about what is required of them.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.7 and 2 have a difference of
Q2.Aisha used 8 coloured pencils for her artwork. Lucas used 4 How many more coloured pencils did Aisha use than Lucas?
Aisha used more coloured pencils than Lucas.
Q3.When playing a game, the difference between Izzy’s score and Lucas’ score is 6, Izzy scored 8 How many points could Lucas have scored?
Q4.16 - 14 =
Q5.20 - = 1
Q6.Which pairs of numbers have the same difference of 2?
Assessment exit quiz
6 Questions
Q1.What equation would represent this worded problem? Group 1 used 7 stones for their microhabitat. Group 2 used 18 stones. How many more stones did Group 2 use than Group 1?
Q2.Which bar model would represent this problem? Group 1 used 7 stones for their microhabitat. Group 2 used 18 stones. Group 2 used 11 more stones than Group 1
Q3.Laura had 14 cookies. She ate 5 of them. How many cookies did Laura have left?
Q4.Laura collected 10 cards and Lucas collected 7 cards. How many cards have they collected altogether?
Q5.On Monday, 4 children rode their bike to school. On Tuesday, 8 children rode their bike. On Wednesday, 6 children rode their bike. In total, how many children rode their bike to school on the 3 days?
Q6.Laura and Jacob score 16 baskets altogether in their basketball game. How many baskets could they have scored each?
To help you plan your 2 maths lesson on: Use knowledge of calculating within 20 to solve problems, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 2 maths lesson on: Use knowledge of calculating within 20 to solve problems, 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 Calculating within 20 unit, dive into the full primary maths curriculum, or learn more about lesson planning.