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G'day I'm Dr Peter Price, welcome back to the free videos that go with the Free Math
Worksheet series. This week we are looking at a set of addition facts called "rainbow
facts". Now rainbow facts--there's another way of referring to them and that simply sums
to 10--so its pairs of numbers which when you add them together you get 10. So if we
write the numbers out from 0 to 10 in a line horizontally and then join together the pairs
of numbers which add together to make 10, whose sum is 10, we can see that we get this
nice rainbow sort of effect, 5 is on its own in the middle of course, because of double
5. So that's the idea behind the "rainbow" and this is something that you could display
in the classroom, to help the students learn the facts. Now I should point out again, a
bit like the doubles facts that I looked at recently, the rainbow facts don't actually
have a cognitive strategy; there isn't a way of thinking about these, "now ok, if I do
this and manipulate that I work out the rainbow fact". It's more a of set of facts that are
really useful, that have, you know, a neat pattern to them, and so we want the students
to become familiar with this group of number facts, so the poster maybe helpful if you
wanted to make a poster like this in your classroom. Another couple of strategies you
could use, one is to simply write out the pairs of facts like this, for the students,
and obviously ask them to work out what the answers are and so on, and they'll come back
and say "Oh look they're all the same" and we'll keep on going here. Another thing the
students may notice, and I would probably ask them "What else can you see?", is that
the pairs are repeated in reverse order, so we have 4 and 6, and 6 and 4; 3 and 7, and
7 and 3; and of course that's the general principle of reversing addition number facts.
OK, so we can help the students with that, in fact if you think about it even if we include
"0 + 10", if I squeeze that in there, there are only six different number facts, we're
not talking about a large number of facts for the students to commit to memory. Now
we can use the 10 frames for this. Because the 10 frame already has 10 spaces and the
students are used to that, we could ask them to do a set of exercises where we say, "Fill
the 10 frame with two different colours, and then write down a number sentence for the
addition of the colours". So here a child could say, "I've got 3 blue ones and 7 yellow
ones and that makes 10". And so students can do a whole set of those and that would help
them to learn these number facts again. The other thing to say about these facts is, although
they're, you know, a sort of somewhat interesting pattern, their real usefulness comes in to
handling money. Because when we go shopping or if our students end up working in a shop,
and we have to work out change, the change is almost always taken away from a number
of tens, either in coins or notes, or 100. So, for example, 100 take away 40, is a number
fact that we can learn from this set of rainbow facts. So they're very very powerful, very
useful, we use them all the time in all sorts of mathematics as well as everyday life. OK
that's it for this week, I hope you've enjoyed it, and I'll talk to you next time.