Race to zero

Hi Barbara.

Hi Michelle, how are you?

I am superb, how are you today?

I'm very well. Umm, are you getting curious?

I'm getting very curious. So I have a new game for us to play today it's called, I'll race you to zero.

I can see some spinners here.

Uh huh, so these are our two starting positions, up here, right at the end of our hundreds chart. Which on this chart, goes to 119.

Okay.

And we both start here and we want to be the first person to get to zero. Ohh, fantastic.

Do we have to land right on zero?

Well, yes.

Okay.

Today we'll play that way, but otherwise at home, you know, you can have some debates and arguments about if you can make a case for going beyond zero.

Ok.

But we'll play that way today.

Ok, great.

Um, so let's, you can get started because the person who starts this game's birthday is closest to February 29th.

Oh ok.

And your birthday is in July.

In July, that's right.

And mine's in November.

Ok, so I get to go first.

Yes, for the calendar year but technically my birthday is closer to November in months.

Oh that's true.

Yeah, so actually I take that back and I'm going first!

I think it should be the person whose birthday is sooner.

Ahh sooner according to today.

Oh that's you then! You, back to you.

Ok great.

So, um, you need to spin both spinners today.

Ok.

Can I spin any one first or it doesn't matter?

It doesnt matter.

Ok 50.

And spin this one.

Zero.

Zero, so you need to make a decision of which number do you want to use. Do you want to use 5 tens, 50 or nothing.

Do I want to stay my same spot or do I want to.

Yeah.

So then I get to subtract 50.

Yes and then you need to tell me what you want to do.

Okay, so I.

If I agree with you, I will move your piece.

Okay, so, since I want to get to zero I definitely I'm going to choose 50.

Uh-huh.

And I think I can probably, because it's a hundreds chart, and it's, the 119 is at the top, I can count down.

Uh-huh.

5 tens, so 5 times, so it would be 5 jumps going down.

By 10 each time.

That's right. So I agree with you because that would be 1 ten, 2 tens, 3 tens, 4 tens. And 5 tens. So 119, 109, 99, 89, 79.

Yes.

Okay. So 119 minus 50 leaves 69.

Okay so I'm now much closer.

You're much closer and now it's my turn to spin.

Okay, great and then will I write it down? With what you're doing?

Yeah ,that's a nice idea, so we can record each other's thinking.

So I got a 7. I'm pretty sure I'm gonna use that. Or a five.

You got 7 tens.

7 tens, oh yeah, thank you. So I'm gonna do that too and Barbara, can you move the pink counter down to 49? Because you subtracted 5 tens and 7 tens is 2 tens more.

Ohhh, so you didn't need to count them. You can just use what you already know.

Yes, I knew on the hundreds chart that each row that we go down decreases by 10 each time. So can you please move me 2 below your blue counter.

Okay, so 2 tens below that. Which is 49.

Yeah, so you would record 119 minus 70 is 49. Okay your go to spin.

I liked, I like your strategy of using what I'd already done to help you.

Thank you.

[Video speeds up and shows some moves being made.]

Or an 8. So 60 is no good to me now because I'm on 49. If I subtract 60, I would end up in negative numbers and we said you've got to land exactly on zero.

That's right.

Okay. Well I could go into negatives but our number chart doesn't have it. So we could draw that on actually, if we wanted to play into negative numbers.

That would be interesting.

Yeah. Would we draw them this way or do we draw another line below?

I think, well, I don't know actually. I'd probably draw it below, just because we will run out of paper.

Right, yeah and makes it sense.

And then it would keep the pattern.

Yeah. Um, so I'm gonna, I think that was an 8, before I moved it, subtract 8 and so if I'm on 49, can you please move me to 41.

Okay.

Because I know the difference between 1 and 9 is 8.

Okay. I'll agree with your thinking there. There you go.

And if I wasn't sure, I could like imagine going 1, 2, 3, 4, 5, 6, 7, 8.

Okay, yeah.

And that would help me. Can you please record my go?

Of course, okay, so we had 49.

[Video show speeds up and has no sound]

Okay and fingers crossed, I spin a 1. Ohhh, a 9.

So, are you missing a turn or are you going back to 25?

Well you can play one of two rules, you miss a turn or you have to go and because I would end up less than zero I come back to 25.

Okay.

How do you want to play?

I think that's probably more fun because otherwise we're just gonna be waiting for you to role, spin a 1.

Yeah, let's play that way.

Which could take long time and now it means that you can use the tens again if you want to.

That's true.

So that makes it a little bit more fun.

I can spin this way cuz I've been a little bit unlucky with my spins. What do you think? 4 or 3? It's like 3 and a half.

Ummm, I will let you choose.

Okay, uh, well I'll choose 4, just so I can get a little bit closer.

Okay.

[Video speeds up and has no sound]

All right mathematicians. What's the mathematics? And so, some of the mathematics with this game is that it helps us develop confidence in using a range of strategies for subtract, subtraction. So, by using a number chart we can use our knowledge of place value and some key mathematical relationships and patterns as we work with numbers.

Have fun playing!