Use knowledge of calculating within 20 to solve problems | Maths

Starter quiz

7 and 2 have a difference of ______

'5' ✓
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.

'4' ✓
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?

14 ✓

12

8

2 ✓
16 - 14 = ______

'2' ✓
20 - ______ = 1

'19' ✓
Which pairs of numbers have the same difference of 2?

3 and 6

3 and 5 ✓

3 and 2

3 and 1 ✓

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?

7 - 18 = ___

18 - 7 = ___ ✓

___ - 7 = 18
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
Laura had 14 cookies. She ate 5 of them. How many cookies did Laura have left?

'9' ✓
Laura collected 10 cards and Lucas collected 7 cards. How many cards have they collected altogether?

'17' ✓
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?

'18' ✓
Laura and Jacob score 16 baskets altogether in their basketball game. How many baskets could they have scored each?

10 and 7

6 and 9

9 and 7 ✓

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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.

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.

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.