Download Using number lines for addition and subtraction. Ordering numbers

Using number lines for addition and subtraction.
Ordering numbers and ‘marked’ number lines.
Number lines use the idea of counting on and back to help teach children
to add and subtract. Starting in reception, children learn to order
numbers, so that they count on from left to right.
Children can then use these ordered numbers to help with calculations.
They count on, along the number line from left to right to add, and count
back, from right to left to subtract.
3+2=5
+1
+1
_______________________________________
0
1
2
3
4
5
6
7
8
9
6–3=3
-1
-1
-1
_______________________________________
0
1
2
3
4
5
6 7 8 9 10
As children progress, they are taught to count on and back by making
jumps greater than 1.
14 + 15 = 29
0 1
2 3
4 5 6
+10
7 8
+4
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
It is always best to start with the higher number and add on the lower
number, as this requires fewer ‘jumps’ and is therefore easier to work
out.
Empty number lines.
Finally, once pupils are secure with this concept, they start to create
their own empty number lines.
These are the same as the number lines they have learned to use, except
that instead of starting from 0, children can begin their number line from
the number they are working with, and only need to mark on the jumps
they make.
They start by counting in tens and units, for example;
34 + 23 = 57
+10
+10
+1 +1 +1
34
44
54 55 56 57
Then progress to counting on the tens in one jump, and the units in a
second jump.
47 – 23 = 24
-3
24
-20
27
47
When using either marked, or empty number lines, pupils’ learning should
be supported by equipment as much as is needed to help secure their
understanding of the concepts of addition and subtraction. Money, toys,
counters, sweets etc – anything can be used to physically add two
quantities together, or take one away from the other to help model how
number lines link to the actual process of adding and subtracting.