Pinch a ten

Welcome back mathematicians.

We're here today to play a game to learn from Marilyn Burns called Pinch a 10. To do this, we have a table, we're going to use to record our moves.

We need some counters, or you could use some dried beans or pasta at home.

And in case I need some support in determining how many I have, I also have this tracing of my hands that one of my other little mathematician friends did to help me with play this game.

So what I do is I stick my hand into my counters and I pinch what I think will be about 10.

So for me at the moment to work out how many I have, I know a couple of structures that I can use and I know some things about 10.

So, for example, one of the things I know about 10, is that when I have five of something and five or something, it always combines to make 10 of something.

But I know that five can also look like this, and because I can't make 2 fives on a dice pattern, I know that I must have less than 10. And in fact, I know this is 5, 6, 7, 8 or I could count them all 1, 2, 3, 4, 5, 6, 7, 8. The important thing is that we work with the students to get them reasoning, as well as counting, to workout how many. So in my first attempt I had less than 10, so I'll put that there to say I had less than 10.

OK, I think I have 10 this time, so let's see I definitely feel like I have more than I had before. So, so this one I might show you my strategy that Holly and Sam showed me.

And that is that. I know that I have 10 fingers and so what I can do is just move each counter under the tip of one of my fingers.

And because there's two empty spaces, I know that I still have less than 10. In actual fact, I have two left and that means I still have 8, exactly like I had last time, even though it felt like it was a bit more.

I could also prove it's 8 because I could pick up both of these stacks really carefully, and if I lay them like this, you can see that they're the exact same height, so I can use direct comparison to say they're both 8 and 8 is less than 10.

Ok, Let's try this one.

OK. So let's check these, once again, I'm going to try my 5 strategy and again I have eight and again I have less than 10. I almost grabbed another few, but I didn't. So next time I need to see if I can estimate a little bit closer, let's try it.

So maybe this time I'll just grab an extra 1 and see what happens. It does feel fuller and I might use this strategy again, so I know I have 10 fingers and so if I have one counter for each fingertip that means that I'll have 10 if I can't fill them all in, I'll have less than 10 and if I have too many, I'll have some counters left over on the other side. Oh and things are looking good since all of my fingers are covered, and I have 10 fingers, I must have exactly 10 counters.

OK, so in my fourth attempt I managed to pinch a ten.

[Silent footage of adult pinching more counters]

O h no, and I was one away and I know I'm one away because if this were a five also would have a counter here like this. It doesn't and so it's one less than 10 which is 9.

So I'm pretty good at getting less than 10, just not so great at making 10 or getting too many. Let's see what happens this time.

Okay, I'm just going to get a big bunch this time and see what happens. So, I know well I'm going to use my 5 strategy 'cause I know 2 fives. Makes 10.

And this time I think I have too many, so let's have a look on my fingers to check. If I move this over so I know I have 10 fingers. If I can put one counter for each finger, that would be exactly 10.

But in this case I have these two leftover. So on my sixth attempt of playing Pinch a ten, I got more than 10.

Over to you, little mathematicians.