# Number Bonds

Number Bonds are the addition and subtraction of 2 numbers as instantly recallable facts. Our school use the structure provided by ‘Learn Its’ to help your child build up these facts, term by term.

Komodo have a great article on number bonds for parents here. It is crucial to note that ‘Learn It’ number bonds are not just 2 numbers that equal 10. They are any addition or subtraction calculation under 20 (e.g. 1+3, 17-9, 6+4, 14-5 etc). Maths No Problem also have a parent video on number bonds (second video down).

Here are some general pointers when helping your child build up their ability to recall number bonds as facts:

• Near doubles. When learning numbers that are adjacent to each other (3+2, 4+5, 7+6 etc), guide your child to use their knowledge of doubles to help them. So 3+2 can be seen as either 2+2 then add 1 or 3+3 then subtract 1.
• Use counters or lego bricks etc to group the double together, leaving the extra ‘1’ separate so your child can ‘see’ the double and the additional 1 needed.
• A tens frame is a useful model to use
• Commutativity. This is understanding that addition can be done in any order. So knowing 5+3 as a fact means you also know 3+5.
• Use counters or lego bricks etc to show the 2 numbers as 2 groups (e.g. 3+5 would have one group of 3 counters and another of 5 counters). Get your child to count the 2 groups. Now physically move the 2 groups around. Get your child to count the 2 groups again and discuss that it is the same total which means it doesn’t matter which order they are done.
• A tens frame is a useful model to use
• A part-part whole model is useful to use
• Inverse. This is understanding that the inverse (opposite) of addition is subtraction. So that if you know 5+4=9 then you know 9-5=4.
• Use counters or lego bricks etc to build 5+4, for example. Get your child to count these amounts to find 9. Then get them to push the 2 groups (5 and 4) together. Ask again, how many do we have? 9. Then ask then to subtract 5, moving 5 objects away from the 9. Ask how many is left? 4. Discuss that these were the same numbers as before but in reverse.
• A part-part whole model is useful to use
• Fact families. a fact family consists of 4 calculations. These use understanding of commutativity and the inverse. The idea is that if your child knows 1 calculation as an instantly recallable fact, they can use that knowledge to very quickly know the other facts for that family. You can get your child to write a fact family down for an individual calculation they already know as a fact (making sure that fact is correct to start with!). As an example, the fact family for 8, 5 and 13 are:
• 5+8=13
• 8+5=13
• 13-8=5
• 13-5=8