# Race to zero (subtracting tens and ones)

Stage 1 and 2 – A thinking mathematically context for practise resource focused on developing flexible additive strategies and reasoning

## 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, 2023

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

• MAO-WM-01
• MA2-AR-01

You will need:

• 2 counters

• 2 paperclips

## Watch

Watch the Race to zero (subtracting tens and ones) video (0:17).

Reach 0 on a 0-119 number chart using subtraction.

[Text over a white background: What’s (some of) the mathematics? This game helps us develop confidence using a range of strategies for subtraction. 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.]

### Speaker

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.

[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]

## Instructions

• Players place their counters at the end of 119.
• The person whose birthday is closest to February 29 goes first.

• Players take turns to spin both spinners and decide which to use, subtracting the amount from their current position. For example, a player rolled 60 and 4. He or she can choose to subtract 60 or 4. Players explain where they need to move their counter to and explain their thinking. If their partner agrees, they move the counter to the corresponding position.

• Players take turns until someone has been able to land exactly on zero.

• Players miss a turn if they can not move. If a roll means they would move into negative numbers, they have to move their counter back to 25.

## Another way to play

Players could use the same gameboard with two different coloured markers. The winner is the person who fills in the most numbers, or, who fills in the final place on the pathway.

## Reflection

• Explain why you chose to create a particlar number. For example, when you rolled 5 and 2, why did you choose to create 52 instead of 25?

• What thinking did you do to decide where to place numbers on the gameboard?

• Imagine you have a space available between 34 and 41. What are all of the possible numbers that could be placed on those two spaces? What are you hoping to roll to fill it?

• What numbers, if any, could you make where you know exactly where to put them almost every time? Which numbers are they? Where would you out them? And Why?

• If you were to replay this game, are there any things you would do differently? Why?