Monthly Archives: October 2014

236. An Emerald Adventure

There are assorted holidays coming up and the weather is getting grim. Time to put your feet up and exercise your brain.

Mathematics of Oz

If you like killer Sudokus, logic problems and applied Maths, you’ll love this book. It follows the adventures of Dorothy Gale as she battles her wits against Dr Oz in her journey through the alien world of Oz. The problems are graded so you can work your way up to the harder questions.

You can download a free sample here: Cambridge Press

Buy on Amazon (UK)

I have used problems from this book with all ages of senior school student from able Year 8 to Further Maths A-level students. A word of warning though – check the difficulty level before you let students loose on the problems!

235. Which witch is which?

Whether you are on half term holiday this week or next, I’m sure you’ll have time for this little number skills starter.

worst witch

Image Credit: Jill Murphy, ‘The Worst Witch’ – a children’s classic, which I highly recommend.

Can you help Wanda, the Grand High Witch, to find the local reporter hiding at her Halloween Girls Night Out? Solve the number problems and unveil the imposter.

Which witch is which? (pdf)

This starter or homework activity includes order of operations, factors, prime numbers, addition and multiplying (written method).

Happy Halloween!

(Updated: 1st Nov 2017)

234. (Students) cubed

Here is a quick fun starter to get your class thinking about dimensions and volume.

Question: How many students can you fit into a metre cube?

The discussion will probably include:

  • ‘How big is a metre?’ (find a metre stick)
  • ‘Did you mean standing in a square?’ (no)
  • ‘How big is the student?’ (average – that answer annoys students)
  • And finally ‘Huh?’ (ask the person next to you to explain)

Whilst this is going on make a metre square on the wall and the floor, using duct tape. The inner measurements of the cube are 1m, the rest is just tape border.


The Predictions
Draw up a quick tally chart of how many students they think will fit. A bright child will usually ask how are you going to find out. Easy …

Put students in the cube
Let them put themselves into the confines of the cube. Cue bouncy boys squashing up. Then remind them it can’t be higher than a metre. You might find it useful to have two spare students hold metre sticks vertically at the non-wall end to define the end of the cube.

We managed nine boys, plus gaps at the top for bits of a tenth boy – it wasn’t ethical to chop one up and sprinkle the bits. So we imagined the tenth person balanced on the gaps around their shoulders.

Ten? That is a new record for this activity!


The Point

  • Volume is the space inside a 3D shape.
  • One metre cube is bigger than you think.
  • It’s a memorable activity to refer back to.

Even better if …

I’d love to get sturdy board covered in birthday (or Christmas) paper to put under and around the cube to start a discussion about surface area. You could make a big show of unfolding the cube and laying the wrapping out on the floor to form a huge net.


I used to do this by taping metre sticks into a cube, but they fell apart easily. In some schools three metre sticks is a challenge, twelve would be a miracle find. Duct tape works much better!

233. Summary Statistics

If you are reading this blog there is a high probability that you are a maths teacher – it is a maths education blog after all. That means data shouldn’t be scary … should it?

scary data

Image credit: (This website is worth a look!)

In a world of performance tracking and data analysis, seeing the trends in class data should be easy. However busy lives and hectic timetables mean we often don’t get the time to step back and reflect on our classes.

I decided to pull together the summary data for each of my classes onto one page. I can see a profile of current and target grades (FFTD*), gender, SEN and Ever6** information in one table. The actual act of completing the table made me take a closer look at the abilities and issues within the class. I realise not everyone uses these data measures so the files are in .doc and .docx form. Since the data is summarised it remains relatively anonymous, making it a good discussion document for trainee teachers or CPD.

You can download a customisable form here:
Summary Data for class KS3 (doc)
Summary Data for class KS3 (docx)
Summary Data for class KS4 (doc)
Summary Data for class KS4 (docx)
Summary Data for class KS4 sample (doc)
Summary Data for class KS4 sample (docx)

*FFTD means Fischer Family Trust Data

**Ever6 is a UK measure related to eligibility for Pupil Premium funding (simplified description).

233. Stealthy Cone Investigation

I like to encourage students to discover rules and formulae for themselves. It’s important that students understand where the maths comes from so they can apply their skills effectively. They also don’t have to rely on remembering a rule (which they may forget when they are stressed).

net of a cone

Image credit:

This resource is a neat and effective way to investigate the surface area of a cone through measuring circles and creating a 3D shape. Students get a physical feel for how the dimensions fit together. Throughout the lesson I let students choose their degree of accuracy in cutting, measuring and calculating. Of course, when we discussed the ‘solution’ at the end of the session it was impossible for me to put one correct answer on the board. So I generalised using a and b for the radii – explaining that everyone could check their method in general terms. The lovely ‘penny drop’ moment happened when my a’s and b’s suddenly became a general rule. I’d conned the class into using algebra because of the accuracy issue.

Download the worksheet and answers here: Surface_area_of_a_cone

Hint: Copying onto coloured paper or card makes this activity stand out in their notes.