Guess my number
ES1 – A thinking mathematically context for practise exploring comparative relationships between numbers to 10.
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
You will need:
numeral cards 1-10 (optional)
pencils or markers
your mathematics workbook.
Watch Guess my number video (2:09).
(Duration: 2 minutes 9 seconds)
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.]
OK, sounds like fun. What's this game called again?
Guess my number!
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.
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.]
Are you showing everybody at home?
[Holly shows her selected card to everyone at home.]
Oh, don't peek.
I'm not peeking.
Alright, you can go now.
What is my number?
Is it, 3?
It is higher than 3.
So, can it be 1 or 2?
No, it can't be Holly, so I'm going to take away one.
[Sarah removes cards and towers for one and 2.]
It can't be 3 either.
[Holly removes card 3 and tower.]
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.
Oh, it's lower than 7.
It can't be 8 and it can't be 7.
[Holly removes card and towers for 7 and 8.]
OK, so it's 4, 5 and 6.
Alright, I've got one more guess. OK. Is the lucky number 4?
Ding ding ding ding!
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]
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.
What is an effective strategy to guess the number quickly?
If you played the game again tomorrow, what would you do differently? Why?
Share your work with your class on your digital platform. You may like to:
share your responses to the reflection questions
share pictures of your work
comment on the work of others.