Guess my number

ES1 – a thinking mathematically context for practise exploring comparative relationships between numbers to 10.

Syllabus

Syllabus outcomes and content descriptors from Mathematics K–10 Syllabus (2022) © NSW Education Standards Authority (NESA) for and on behalf of the Crown in right of the State of New South Wales, 2024.

Outcomes

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

Collect resources

You will need:

  • numeral cards 1-10 (optional)
  • building blocks
  • pencils or markers
  • your mathematics workbook.

Watch

Watch Guess my number video (2:09).

Guess a number using only 'greater than' or 'less than' as clues.

(Duration: 2 minutes 9 seconds)

Holly

Hi Sarah.

Sarah

Hi Holly.

Holly

So, this time I'm going to... You're gonna guess which number I've got.

[Screen shows cards from the number 1 to 8 in a row. Above the cards are blocks that represent the amount of the numbers on the cards.]

Sarah

OK, sounds like fun. What's this game called again?

Holly

Guess my number!

Sarah

OK, alright, so maybe I'll close my eyes where you choose, and you can show everybody who's watching the number that you chose.

Holly

Yeah. So which number should I choose?

[Screen shows Holly with the deck on cards fanning them out to select one card.]

Alright. I choose this one....

[Holly selects a card with number 4.]

Sarah

Are you showing everybody at home?

[Holly shows her selected card to everyone at home.]

Holly

Oh, don't peek.

Sarah

I'm not peeking.

Holly

Alright, you can go now.

Sarah

OK.

Holly

What is my number?

Sarah

Is it, 3?

Holly

Higher.

Sarah

It is higher than 3.

Holly

So, can it be 1 or 2?

Sarah

No, it can't be Holly, so I'm going to take away one.

[Sarah removes cards and towers for one and 2.]

Holly

It can't be 3 either.

[Holly removes card 3 and tower.]

Sarah

You're right because you said it was higher than 3. OK, so I only get 3 guesses. Is that right?

OK, so I've used up one guess alright. OK. Is the number 7.

Holly

No. Lower.

Sarah

Oh, it's lower than 7.

Holly

It can't be 8 and it can't be 7.

[Holly removes card and towers for 7 and 8.]

Sarah

OK, so it's 4, 5 and 6.

Alright, I've got one more guess. OK. Is the lucky number 4?

Holly

Ding ding ding ding!

Sarah

Yay. Thanks Holly, thanks for playing with me.

I wonder if some other people would like to play this game and maybe they could even do numbers larger than eight.

What if it was one to 20? I wonder how hard that would be?

Alright, signing out mathematicians.

[End of transcript]

Instructions

  • Write the numbers from 1 to 10 (for example) on a piece of paper or use cards to set the number range. For example, this student chose to use the numbers between 1 and 8.
  • Ask someone at home (the ‘secret holder’) to choose a secret number within your given range.
  • Guess the ‘secret' holder’s number.
  • They will tell you whether their number is greater or less than your guess.
  • Try to guess the secret number in the fewest number of guesses possible, or, with only 3 guesses.

Reflection

  • What is an effective strategy to guess the number quickly?
  • If you played the game again tomorrow, what would you do differently? Why?

Share/submit

Share your work with your class on your digital platform. You may like to:​

  • share your responses to the reflection questions
  • write comments​
  • share pictures of your work​
  • comment on the work of others.

Category:

  • Early Stage 1
  • Mathematics (2022)
  • Representing whole numbers

Business Unit:

  • Curriculum and Reform
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