# Rekenrek duel level 2

This is a thinking mathematically context for practise focussed on developing knowledge of part-part-whole relationships, benchmark numbers and thinking flexibly about numbers.

## Syllabus

Syllabus outcomes and content descriptors from Mathematics K-10 Syllabus © NSW Education Standards Authority (NESA) for and on behalf of the Crown in right of the State of New South Wales, 2021

• MAO-WM-01
• MAE-CSQ-01
• MAE-CSQ-02
• MAE-RWN-01
• MAE-RWN-02
• MAE-FG-02

• MAO-WM-01
• MA1-RWN-02
• MA1-CSQ-01
• MA1-FG-01

## Collect resources

You will need:

• a rekenrek each (you can learn how to make a rekenrek here)

• a set of numeral cards from zero – 20

• paper

• markers or pencils.

## Watch

Watch Rekenreks duel level 2 video (6:25).

Represent numbers from zero – 20 on a rekenrek in different ways.

### Transcript of Rekenrek duel level 2 video

[Text over a navy-blue background: Rekenrek duel: level 2. 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, 2 rekenreks are laid out on a blue sheet of paper, one above the other. Both rekenreks consist of 2 thin, parallel, wooden sticks, held in place by wooden clothes peg. Each stick features a group of 5 red beads and a group of 5 blue beads, which are pushed together on the right side of both rekenreks.

To the left of the rekenreks, are two animal toys; a giraffe by the top rekenrek and a lion by the bottom rekenrek. To the right of the rekenreks, is a stack of small, white, square pieces of paper. To the right of that is a cup filled with dry pasta shells.]

### Speaker:

Hello, mathematicians. We hope you're having an amazing day today. We wanted to show you a game called Rekenrek Duel. You might have seen one way to play this, and we'd like to show you another way that really makes your brain think super hard. So, back to play Rekenrek Duel is the king of the jungle here, our lion. (Roars) And also our giraffe, who, as luck would have it, his head keeps falling off, not falling off, but popping out of the photo. I think giraffes would probably have this problem very often, they're so tall. So, in this case we also need some counters. So, today we're using dried pasta for our counters and we need some number cards from zero through to 20.

[The speaker grabs a sheet of white paper and lays it in the work area. She grabs 2, coloured markers. She lays the stack of number cards – the squares of paper – face down on the larger sheet of white paper.]

### Speaker:

And this time the way that we play, we also need some cardboard or paper to record on, is the players, the lion, the king of the jungle, and the tallest of the jungle, maybe, have to... That could lead into an interesting debate on why the lion is the king of the jungle, 'cause the giraffe is taller. So, you could say the giraffe is the tallest, the king of the jungle, because they're the tallest.

I should keep going. OK. You might be saying, but maybe an elephant's bigger. Maybe. Let's play. So, what we need to do is, in this case, turn over a card.

[The speaker turns over the number card on top of the pile. It features a numeral 7 and the word ‘seven'.]

### Speaker:

So, we're going to work with 7 and these guys have to take it in turns until they can't think of any other ways to make 7 on the rekenrek using just one or 2 slides. So, let's play. The lion is going to be represented by the black marker and the giraffe will be represented in orange on our game over here. So, the lion can start first, and the lion might think, 'Well, I know 7 is double 3 and one more'. So, double 3 looks like this…

[On the lion’s rekenrek, the speaker slides 3 red beads on each row across to the left. The slide one more red bead on the bottom row over to the left.]

### Speaker:

..which is 6, and one more makes 7.

[In black marker pen, beside the lion’s rekenrek, the speaker writes '7 is double 3 and 1 more'. The speaker slides the red beads on the lion’s rekenrek back to the right.]

### Speaker:

So, records 7 is double 3 and one more. And now giraffe needs to think of another way to make 7 that's different in one or 2 slides. So, the giraffe might think, 'Well, I know that seven is five and two'. Was that what you guys were thinking? Oh, nice thinking, like the giraffe.

[On the giraffe’s rekenrek, the speaker moves 5 red beads on the top row to the left.]

### Speaker:

So, in one slide can move across five…

[The speaker moves 2 red beads on the bottom row back to the right.]

### Speaker:

..and in another move can slide across two.

[In orange marker, beside the giraffe’s rekenrek, the speaker writes '7 is 5 and 2’.]

### Speaker:

So, it can record seven is five and two.

[The speaker moves the beads on the giraffe’s rekenrek back to the right.]

### Speaker:

And now it's back to the lion and the lion might think, 'Oh, well, actually, I know that 7 is 3 less than 10.' Yes. Some of you had that idea. Good idea.

[On the lion’s rekenrek, the speaker traces her finger along the first 3 blue beads from the right on the top row. She separates the remaining 7 beads by pushing them to the left slightly.]

### Speaker:

So, there's 3, 'cause my brain can subitise that many.

[The speaker moves the 7 beads all the way to the left of the lion’s rekenrek.]

### Speaker:

And so, I can move this across in one slide and say this is seven because it's 3 less than 10.

[In black marker pen, the speaker writes, '7 is 3 less than 10'. She slides the beads on the lion’s rekenrek all the way to the right.]

### Speaker:

So, seven is three less than ten. Oh, OK. Now the giraffe is having to think hard, and he could say, "Oh, hold on a second, seven is three and four." Some of you have that one? Aha.

[On the top row of the giraffe’s rekenrek, the speaker moves 3 red beads to the left. On the bottom row, she moves 4 red beads to the left.]

### Speaker:

So, there's 3 and 4 in two slides. Yes. And it is similar to this idea of double 3 and one more, but it's different because they have named it differently and they have said 3 and 4 and looked at chunks of 3 and 4, whereas here it was 2 chunks of 3 and one more.

[In orange marker pen, the speaker writes, '7 is 3 and 4'. The speaker moves the beads on the giraffe’s rekenrek back to the right.]

### Speaker:

So, 7, and you can have some nice debates about that with your friends that you're playing with. 7 is 3 and 4. OK, lion, back to you. And now the lion's thinking, 'Oh, what else could I do?' I know.

What about, seven is six and one? Yes. So, how could we make six in one slide?

[The speaker points to the 5 red beads on the top row of the lion’s rekenrek. She points to the blue bead beside them. She slides these beads over to the left.]

### Speaker:

Yeah, we can see here's a chunk of 5 and one more is 6.

[She slides one red bead on the bottom row over to the left.]

### Speaker:

And yes, one makes 7.

[In black marker pen, the speaker writes '7 is 6 and 1'. She slides the beads back to the right.]

### Speaker:

So, seven is six and one. OK. Oh, now, giraffe. Oh, I think the giraffe has one. What about that 7 is 13 less than 20? Yes. So, that means they need to leave behind one whole 10 and leave behind 3 more.

[On the top row of the giraffe’s rekenrek, the speaker slides 7 beads to the left.]

### Speaker:

So, that should be seven.

[In orange marker pen, the speaker writes, '7 is 13 less than 20'. The speaker slides the beads on the giraffe’s rekenrek back to the right.]

### Speaker:

So, they could say seven is 13 less than 20. Oh, that was a good play by the giraffe. And now the lion's thinking, 'I can't think of any others that I could say.'

[The speaker places a dry pasta shell beside the giraffe.]

### Speaker:

And so, in this round, the token goes to the giraffe, 'cause the giraffe was the last person to come up with an idea.

[The speaker places the 7 card face down on the bottom of the pile. She flips over the top card. It has a numeral 9 and the word ‘nine’.]

### Speaker:

And they put the card to the bottom, and they start again.

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

### Speaker:

Over to you, mathematicians, to play Rekenrek Duel Level Two.

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

### Speaker:

So, what's some of the mathematics here?

[Text on a white background: What’s (some of) the mathematics?
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.

[Over a grey background, the red waratah of the NSW Government logo appears amongst red, white and blue circles. Text: Copyright State of New South Wales (Department of Education), 2021.]

[End of transcript]