Two is the magic number

I’ve been thinking a lot about misconceptions recently and also revisited a couple of old posts looking for stuff to use for revision when I came across my revision mat idea ( HERE ) that was produced using ideas that were “twitter-sourced” and it has got me thinking.  I really want to get students exploring ways in which they can check their answers using strategies such as changing decimals to fractions to see if the process for  “multiplication” that they have applied still works or trying different (simpler?) numbers and again, exploring if the rule they have applied still works.

I am a bit dubious about deliberately using “wrong” answers as I really don’t want to leave the students thinking that any of the “wrong” answers are actually correct so it needs to be delivered really carefully. I’m thinking that after the students have attempted to work out which two are the correct answers – we’ll discuss generally what strategies they are using (with a view to developing a list of “checking your answer strategies”) that they can then use to prove that the answers are correct/incorrect in a more formal way by sticking each one in their book and showing around it what the correct answer is (that’s the first thing I’d like them to come up with themselves is that you attempt the question yourself **fingers crossed**) and also show what they can do to show that they’ve tested the answer stands up to scrutiny.

Anyway that’s my plan .. we’ll see! Now this is where the “crowd-sourcing” comes in: If you have any misconceptions you think I should add to a later worksheet – I’m thinking that this could be a type of worksheet that each year group could get every so often (it’ll be good to embed the practice of proving/disproving an answer into year 7 early too) please leave me a comment below with any common misconceptions or mail me: [email protected]

So far I’ve done 3 (UPDATED SUNDAY NIGHT 1st March!! … so you may need to download correct versions!) :

Two is the magic number 1

Two is the magic number 2

Two is the magic number 3

two is the magic number 1

two is the magic number 2two is the magic number 3

2015-03-05T19:00:07+00:00February 28th, 2015|5 - Misc., Blog, Teaching|


  1. Shaun February 28, 2015 at 2:06 pm

    Great Idea. One I’ve spotted a lot and now discuss regularly is “What is 4x^2 when x=2”. 64 is a really common answer and is great in a multiple choice hinge question.

  2. Mel February 28, 2015 at 2:20 pm

    Brilliant .. thank you.

  3. […] Muldowney (@just_maths) has put together this lovely post entitled “Two is the magic number” sharing some resources aimed at wiping out misconceptions and checking […]

  4. Gareth May 18, 2015 at 11:43 am

    These are excellent. Great for revision, great design, great for discussion. Thank you! Please, please, please share some more if you can!

  5. Mel May 18, 2015 at 11:31 pm

    aw shucks! glad you like them … summer job to make some more! focus is all about year 11 at the minute 🙂

  6. Debbie June 5, 2015 at 12:14 pm

    I used the first activity with my Y9 class as a lesson starter. It was very well received indeed. All pupils were most complimentary when evaluating the task, describing it as as making them think and recall previous knowledge in a fun way.

  7. Mel June 5, 2015 at 12:46 pm

    That’s great to hear ☺️

  8. […] activities called “Two is the Magic Number” from Just Maths. Each one is a collection of cards solving a short problem, only two of […]

  9. mathcurmudgeon April 19, 2016 at 3:08 pm

    Looks like more fuel for

    “Do This and The Bunny Dies”

  10. […] activities called “Two is the Magic Number” from Just Maths. Each one is a collection of cards solving a short problem, only two of […]

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