Tip:
Highlight text to annotate it
X
G'day everyone, I'm Dr Peter Price of Classroom Professor. Welcome to this video, this is
an extension of last weeks' topic which was Rainbow Facts, this week we're looking at
"Rainbow Facts to 100 and also the 7x number Facts". The reason I'm putting the two together
is that's what's on the worksheets that accompany this video and the worksheets come from a
revision book of facts, so they're a variety of strategies, we packed them all into one
book, and so most worksheets have a couple of strategies for the students to revise.
So rainbow facts to 100 really extends the students' knowledge of the simpler, plain,
standard, basic rainbow facts up to 10, and it does it in a couple of different ways,
so the first one is a pretty easy one, and that's looking at multiples of 10. So just
as the students know for example that "4 +6 = 10" they should be able to extend that knowledge
once they're familiar with the multiples of 10 and the number 100, that 4 tens and 6 tens
is "10 tens or 100", and so that's a number fact that they should pretty easily be familiar
with. We can use a number line to show the same thing, so we're not drawing the rainbow
this time, although you could possible do that, but just the idea that we've got numbers
up to 100 here, this is all the numbers to 100. If we said this start with a hop to 30,
"How much more do we need to get up to 100, or 30 + ? = 100?" That's the idea of a rainbow
fact up to 100. But that's only looking at multiples of 10, obviously we've got a lot
of other numbers between them, so we have numbers comprised of tens and ones, we can
extend the same thinking. So let's take another example, supposing we've just done 30, let's
make it "32 plus something, equals 100". We could use the number line for these, number
lines are quite useful for helping students think about facts based on other facts, so
if you already know 30 + 70 = 100, "How can you do 32?" So let's jump across to 32, there
we go, "How much more is there?" "Well it's not going to be 70 is it?" Because 70 was
the answer when we only start, our first hop was to 30, this is a little bit beyond that,
so the two has to be taken away from 70, and of course this will be, "68". And there's
a variety of different ways we could help the students to understand that. My approach
quite honestly would be to put the challenge up to the students and say, "Well you know
what 30 is, I want you to work it out, think for yourself, you know develop your mathematical
thinking". And so the idea of compensation, adding a bit more here to take a bit
more off the other number is a useful mathematical skill for doing a whole lot of mathematical,
oh sorry, mental computation. Let's look quickly at the 7x facts--so we'll move on from the
rainbow facts to 100--how can we approach this, and what's the strategy? Because
as you'd be aware if you've watched my other videos, we adopt a strategies, approach, we
recommend that for teaching all of the number facts for all four operations, and specifically
for multiplication, we've got the doubles, we've got the double doubles, we've got place
value base strategy for the 10x and 5x, "What do we do for sevens?" Well the answer is,
there isn't really a neat strategy for them, because the sevens are, they are not any straight-
forward patterns in the sevens, there are tricky ways you can do it, but there aren't
any nice straightforward ones. So my approach should be to do something like this, let's
start with listing all the number facts that we need to know, like so. And I'm going to
stop at 10 although obviously you could go to 12; depending on where you teach, students
may be only required to go to 10 or they may be asked to go to 12, but let's stop at 10
for the sake of this exercise. And then look at which ones students already know, we could
ask the students, "Which ones do you find easy?" You know, "Tell me the ones that you
already know, the ones that you just straight off at the top of your head you know what
they are". well 7 zeros is nice and easy that's going to be 0; 7 ones are 7; 7 twos
are 14; 7 tens are 70, so there's a few knocked off, we know 7 threes, because
that's a bit more than 7 twos, we add another 7; 7 fours we can get from 7 twos, by doubling
again; 7 fives--the 5x are all easy, they end in "0" or "5", and there are ways to think about
which one the answer is. And 7 nines we've got lots and lots of patterns; we can use
our fingers, etc., etc. Look at that, we're only left with three, so I would point out to
students that these are probably the most difficult three and really we've done all
the others before, in fact we've done these before as well, because if we've already done
the sixes and the eights, which I would recommend that you do, because there are little bit
easier than the sevens, then there's really only "7 x 7" which is a square number. So
basically if we focus our attention on those three, in particular, again this is the sort
of thing that you could put onto a poster for students, just for them to look at and to
remind them of what they've learned about this particular set of number facts, these
are the tricky ones, these are the ones you should spend the most time on. I remember
telling students when we had number fact competitions regularly each week, that if I wanted to trip
them up, If I wanted to give them the hardest number fact I could think of up to 10 x 10
that was "7 x 8" and so they went home and learned that particular number fact which
of course was a benefit to them. So that's the approach I recommend to doing the 7 times number
facts, we've come to the end of the video and I'll talk to you next time.