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[Text over a navy-blue background: Rekenrek duel: level 1. The NSW Government logo is in the lower left-hand corner of the screen. Small font text at the top of the screen reads: NSW Department of Education.

A title on a white background reads: You will need…
Bullet points below read:

• a rekenrek each
• a set of numeral cards 0-20
• some paper
• markers or pencils

On a table, two rekenreks lay on a blue sheet of paper, one above the other. To the left of the rekenreks, are two animal toys. Beside the top rekenrek is a giraffe. Beside the bottom rekenrek is a lion. To the right of the rekenreks, is a sheet of white paper. On top of that is a stack of small, square pieces of paper.

On each line of the rekenrek’s the five red beads and five blue beads are all pushed to the right-hand side.]

Speaker:

Hello there, mathematicians, we hope you having a really lovely day today. We are gonna show you a new game called Rekenrek Duel. Now there's lots of different ways you can play this game and we're gonna show you one way today. And today playing our game is our king of the jungle, the Great Lion.

[The speaker picks up the lion and shows it to camera. She points to the giraffe. She pulls it down so its head is in the frame.]

Speaker:

And we also have our giraffe. And I think actually, well, this is quite fitting, actually. His head's a bit too big, so I'll move him down so that you can see our giraffe.

[She grabs two markers, one black and one orange.]

Speaker:

And we're gonna represent our king of the jungle with black and our giraffe with orange because he's got an orange body or partly orange body.

[The speaker picks up the stack of square pieces of paper. Numbers are written on them. Each one has a different number, expressed as both a numeral and a word. She places them back down, face down. She turns the top card over; it has a number 6.]

Speaker:

So how you play is that you need some number cards from zero through to 20 and you shuffle them up and you put them in the central pile and you turn over a card and the lion can go first today, and he needs to be able to move six across on his Rekenrek in just one or two slides only.

[On the top row of the lion’s rekenrek, the speaker moves the 5 red beads and one blue bead to the left.]

Speaker:

So the lion might think, well, I know 6 is 5 and one more, so that's 2 slots.

[She moves the beads back to the right. She moves 3 red beads on the top line and 3 red beads on the bottom line to the left.]

Speaker:

He could also think, Well, I know 6 is 3 and 3 double 3 is 6.

[She moves the beads back to the right. She moves 3 red beads on the top line and one red bead on the bottom line to the left. She moves the one bead on the bottom back to the right, then moves 2 beads over to the left.]

Speaker:

Or he could say something (unknown) I know 6 is 4, and if I look at this chunky, that's 5 and leave one behind. That's four. And one more is 5, so 4 and 2 is 6.

[On the white sheet of paper, beside the lion’s rekenrek, the speaker writes in black marker, '6 is 4 and 2'. She puts the square piece of paper with the 6 on it to the bottom of the stack. She turns over the card now on top. It has a 16 on it.]

Speaker:

And so then he could say 6 is 4 and 2 and then put the card to the bottom. And it's now giraffe's turn. And giraffe has to make 16 in one or two slides only. So the giraffe is thinking, Oh, what do I know about 16? I know it's one, 10, and 6 more.

[The speaker moves all the beads on the top line of the giraffe’s rekenrek to the left. She then moves 5 red beads and one blue bead on the bottom line.]

Speaker:

So, one slide could be moving across one 10. And then how could I make 6? Yes, because there's a chunk of 5 and one more makes 6. So that's how he could make 16.

[In orange marker, the speaker writes, '16 is 1ten and 6', beside the giraffe’s rekenrek. She places the 16 card on the bottom of the stack. She turns the top card over; it has a number 8 on it. She moves all the beads back to the right.]

Speaker:

So, he has to think about recording 16 is one, 10, and 6. And yes, the card goes on the bottom, and then it's the lion's turn again. OK, mathematicians, how would you make 8 in one move? What are you thinking? One or 2 slides only.

[The speaker moves 4 red beads on the top line of the lion’s rekenrek, then 4 red beads on the bottom line. She moves them back to the left.]

Speaker:

Oh, nice thinking, yeah. So you could do double 4 so if I know this chunk is 5, that means if I leave one behind, this must be 4 because four is one less than 5 look.

So that would be one 4. And I use the same strategy for another four double 4 is 8.

[She moves 8 beads on the top row of the rekenrek. She moves them back to the left.]

Speaker:

Yes, and some of you are thinking, well, you could think about 8 is 2 less than 10. So do the 2 left behind strategy. That is also 8.

[The speaker moves 5 red beads on the top row and 3 red beads on the bottom row.]

Speaker:

Yes, and some of you are thinking 8 is also 5 and 3.

[Text on a blue background: Over to you!]

Speaker:

Alright. Over to you mathematicians to play, Rekenrek Duel.

[Text: What’s (some of) the mathematics?]

Speaker:

So what's some of the mathematics here?

[Title on a white background: What’s (some of) the mathematics?
Bullet points below read:

This game encourages students to:

• think about important relationships such as how many more/less are needed to get the nearest 5 or 10
• notice, develop and use part-part-whole number knowledge
• use numbers flexibly

These are all essential to be able to develop, and use, flexible strategies when working in additive and multiplicative situations.]

Speaker:

This game encourages students to think about important relationships, such as how many more or less are needed to get to the nearest 5 or 10. To notice, develop and use part-part-whole number knowledge and to use numbers flexibly. These are all essential to being able to develop and use flexible strategies when working in additive and multiplicative situations. Have fun mathematicians until we meet again.

[The NSW Government logo flashes on screen. Text below reads: Copyright State of New South Wales (Department of Education), 2021.]