Learning, Teaching and Supporting in Maths

Calculation Strategies

Number Shape, Space and Measures Data Handling Using and Applying Maths

Using and Applying Maths happens in all 3 other strands, as well as in other lessons, such as Science.

Today we will look at number. The four operations (+, -, x and ÷)

I will show you the methods that we teach children to use to add, subtract, multiply and divide. We will also look at some of the resources we use to teach number in School.

The four operations in calculations are grouped into

Adding and Multiplying – where the answer gets bigger

Subtracting and dividing – where the answer gets smaller

We use number lines in all four operations.

We start with numbered lines like this one –

0 1 2 3 4 5 6 7 8 9 10

Then we move on to blank number lines, like this one –

Children add on their own numbers to solve calculation problems.

Children begin in EYFS and Key Stage 1 by adding real objects, such as cubes. They combine sets and count the total.

Count 4 cakes. Count 3 cakes. How many altogether?

+ =

We then move on to using number lines and counting up in ones.

14 + 5 = 19

+1 +1 +1 +1 +1

14 19

Next we learn to partition – split the number into tens and units – to add.

What is 72 + 14?T U70 210 4

70+10= 80 2+4= 6 80+6=86

Now we can add by partitioning –

86 + 57 =

+50 +4 +3

86 136 140 143

Or by rounding then adjusting

754 + 96 (rounding and adjusting)

+100 -4

754 850 854

Finally, we move on to adding in columns, using place value.

HTU ThHTU 597 7648+ 475 and + 1486 12 160 9134 900 1 1 1

1072

Again, multiplication begins with drawings and practical activities.

How many is three lots of 2?

x x x x x x

Now we use the number line for repeated addition.

I have 4 5p coins, how much is that?

x1 x2 x3 x4 0 5p 10p 15p 20p

3 x 4 = 12

4 x 3 = 12

We can partition to multiply using a grid, like this –

72 x 38 = 70 2 30 2100 60

8 560 16

4346 x 8

48 320

240032000 34768

We begin by ‘taking away’, ‘counting back’ and seeing ‘how many left.’

We made 6 mince pies. We ate 2. How many mince pies are left?

x x x x x x

We can use a number line to count back.

22 – 7 =

-5 -2 15 20 22

In Key Stage 2, we count UP the number line to find the difference.

What is the difference between 34 and 72?

+30 +8 34 64 72

First we use partitioning and subtract hundreds, tens and units. 754 – 286 =

H T U700 + 50 + 4

- 200 + 80 + 6 700 + 40 + 14

- 200 + 80 + 6  600 + 140 + 14

- 200 + 80 + 6 400 + 60 + 8  400 + 60 + 8 = 468

5 13 1

6 4 6 7- 2 6 8 4 3 7 8 3

Division starts with practical sharing -

If I share my 12 sweets between 3 people, how many do they each get?

Number lines are also used to count up in division.

A baker bakes 24 buns. She puts 6 in every box. How many boxes can she fill?

x1 x2 x3 x4

0 6 12 18 24

Finally, we can jump in groups and record remainders on the number line.

What is 42 divided by 4? 10 groups (Remainders)

x10 +1 +1

0 40 41 42

Our School is becoming increasingly excellent at teaching these strategies, but we must now move on to applying what we know.

We have recently begun introducing reasoning questions and problem solving tasks into our lessons in order to promote higher order thinking skills (HOTS).

Explaining how you know and answering ‘why?’ questions helps us to understand at a deeper level.

I would like to discuss reasoning, problem solving and the importance of vocabulary in future sessions.

Any other ‘hot’ maths topics?