How your child
learns to calculate:
Addition
Addition with 1 digit numbers and smaller 2 digit numbers:
Skills needed:
1) to be able to count on in ones.
2) To be able to use number bonds to ten.
Children use objects (blocks, toys etc) to help their counting. They recognise
that addition is putting together items into one group, and that they need to
find out how many are in the final group.
In Year 1 children may start using bead strings or a number line to solve
addition problems, counting in ones.
They become able to start with the bigger number and count on to find the
total, rather than needing to re-count everything.
In Year 1 children learn the number bonds to ten (8 + 2, 5 + 5 etc). They
become able to use these number bonds to speed up their addition skills:
Addition with larger 2 digit numbers and beyond (Year 2/3 +):
Skills needed to be able to add successfully:
-
be able to partition numbers
This means knowing that in 23, the 2 is actually 20 (2 tens).
Children need to be able to partition numbers into their individual values,
for example:
(Note: Decimal numbers from Year 4/5)
- to be able to add multiples of 10.
For example, knowing 20 + 30 or 60 + 70
- to know their addition facts for all numbers to 20.
This means knowing that 15 + 5 make 20, or that 12 + 3 makes 15. They
should know these as number facts, rather than have to work them out.
Solving addition, partitioning and using a number line:
-
Children partition both numbers in the calculation
-
they then add the largest digits first, so here it would be the tens. They
use a number line to support their working out:
- they then add on the units to complete the calculation.
Children may do this in different ways, depending on how confident they
are with the numbers. Here are some examples:
Solving addition, partitioning, without the number line:
Using the same method, but without the number line (Year 3 +):
Solving addition, vertical layout:
-
children using this method should understand the partitioning and be
able to do it in their heads.
When first using this method, they continue to add the largest digits
first:
-
using place value to line up the digits is important if children are going
to get the correct answer. This means that all the units line up, all the
tens line up etc:
-
Children then move on to adding the smallest digits first. This prepares
them for being able to add decimal numbers correctly:
When children first start adding decimals (Year 4, in the context of money)
they may feel more comfortable using the number line method again to start
with.
Important note:
All children are different and should be allowed to choose the method that
they feel most comfortable and confident with. Some children will always find
the number line method the best way of working out calculations. This method
will work for any size of numbers, including decimals and fractions, so does
not stop them from progressing in their maths work.