Category Archives: Ratio and Proportion

346. Area & Volume conversion

This is a quick post on how I teach metric unit conversion for area and volume. All you need is a big whiteboard and coloured board pens.

Start by stressing that all diagrams are not to scale/accurate.

Two colours

  1. Draw a square on the board
  2. Pen colour 1: Label it as 1cm
  3. What is the area? Show the calculation
  4. What is 1cm in mm?
  5. Pen colour 2: Label it as 10mm
  6. What is the area in mm? Show the calculation
  7. What is the scale factor between the sides? the area? why?


Three colours

  1. Draw a square on the board
  2. Pen colour 3: Label it as 1m
  3. What is the area? Show the calculation
  4. What is 1m in cm?
  5. Pen colour 2: Label it as 100cm
  6. What is the area in cm? Show the calculation
  7. What is the scale factor between the sides? the area? why?
  8. Repeat in pen colour 1 for mm

Four colours

Well not actually four colours – pens 2,3 & 4 only. Repeat the process for kilometres to metres and centimetres.

Volume – same process, just three dimensions

Why all the colours?

By coding each unit of measurement with a colour students can see the progression of the calculations and the links between area/volume and scale factor. After all, an okay mathematician can reproduce memorised facts, but a great mathematician doesn’t need to memorise – they understand where the calculations came from.

342. Revision jotters

With the exams looming large, I thought I’d share how my class have been revising. To give you some context roughly a third of the class are doing Foundation GCSE, aiming for at least a Grade 4. The rest are doing Higher and aiming for a Grade 5 or better. We have three, one hour, lessons a week. I’m rotating between doing an exam paper, a whole class revision activity (eg a revision clock) and tiered revision.

I know if I tell the students to revise independently the results are going to be mixed. Some will be brilliant, some will be more laid back. To resolve this I pick a topic (or two) from each tier that I know they need to improve on from or that they have requested. It’s helpful if there is a theme to the work. I’ve recently done things like y=mx+c (F) with plotting inequalities (H).

Now the genius part: PixiMaths revision jotters

How to run the session

Photocopy a big stack of revision jotters. If you are doing black and white copying, use the b&w version. We requested the b&w version and, because PixiMaths is awesome, it is now on the website.

Clearly put on the board which topic each tier is revising

Eg Foundation: exact trig values, Higher: trig graphs

Give students 5-10 minutes to fill their revision jotters with everything they know. Have textbooks or maths dictionaries available to fill in the gaps. You may find that Higher students want to do the Foundation topic too – no problem, just make sure they have two jotters. Due to the complexity of the Higher topic, they will need more time to make initial notes.

My students are allowed headphones in revision sessions. At this point it’s headphones in for Higher and out for Foundation.

Do a skills recap on the board (exact trig values), with maybe an exam question too. Students can ask questions on the topic and add to their jotter. Then have a worksheet for students to do eg Corbett Maths or KeshMaths GCSE exam questions booklets. They can refer to their revision jotter or scan the Corbett Maths QR code for extra help.

Swap over. Headphones in for Foundation and out for Higher.

Repeat the process for Higher, with drawing trigonometric graphs. Issue an appropriate worksheet.

Once you’re done, make a judgement call. Are there students who could push it further? Maybe transform a trig graph or problem solve? Go for it. Foundation are busy, Higher are busy, spend some time stretching your most able. Every mark counts.

A huge thank you to PixiMaths for the revision jotters (and everything else).

Examples of students’ work

Shared with permission of students. You can see that they have personalised them to meet their needs and some are a work in progress. Also, the b&w jotter photocopies so nicely.

336. Geometry Snacks

If you are looking for a very last minute gift for that special Mathematician in your life, or you have Christmas money to spend, may I recommend “Geometry Snacks” by Ed Southall (@solvemymaths) and Vincent Pantaloni (@panlepan)?

It is a nearly pocket sized book of geometry puzzles whose construct of simple, elegant problems can decieve the unwary into thinking the solutions are easy. This is a book for those who embrace mathematical rigour, rather than repetitious guesswork.

In fact, forget buying it for someone else – get one just for yourself!

Geometry Snacks is published by Tarquin (ISBN: 9 781911 093701)

311. Sales starter

Here is a neat little starter photograph (click on the image to enlarge) – get the mini whiteboards at the ready!

Sale price starter

Possible questions

  • How much money could be saved with the different reductions?
  • What are the percentage discounts?
  • What is the price as a percentage of the original?
  • What is the exchange rate between pounds and euros (using the original prices)?
  • What would the sale prices be in Euros?

If you can’t read the data clearly, the prices are: £45, £30, £22.50, £13.50, 70 euros

305. Get Carter

Seriously, you need to Get Carter ….

Get Carter 1971 Poster

Or rather head over to the amazing website by Mr Darren Carter: MrCarterMaths.com

I don’t know where to start – in a few clicks you have access to tiered questions on a multitude of topics with answers. Answer in an exercise book or on a mini whiteboard – it’s genius! Another click and the questions change.

If that wasn’t enough, you can print out individual worksheets at each level – differentiation without a headache.

I chose to print out the three tiers and award them points. Bronze = 1 point, Silver = 2 points, Gold = 3 points. I put together a cover sheet with instructions and the students instantly had control of their homework. All I asked for was 20 points of answers. The ones who need the practise can do lots of low scoring questions, the ones who need a challenge can do fewer questions at a harder level. My task is available to download below (full credit to Mr Carter given) – It prints nicely as an A5 booklet.

Tiered Proportion Homework Booklet

Once you’ve visited the site, follow him on Twitter @MrCarterMaths