Pie Charts and Proportions

Just a quick post today - spent most of yesterday planning for teaching pie charts to Year 8 this week (set 4 of 5 in that half of the year group). After a fairly standard drawing pie charts and a fairly standard interpreting pie charts (i.e. basically being able to recreate the frequency table given a piece of information) we are going for a bit more understanding about the proportionality behind pie charts. The two resources I had on pie charts and algebra I am saving for GCSE, but I did design a nice activity as part of a RAG worksheet that I will use (it is the Amber activity, with the Red being some simple write down the proportions shown and the Green being a lovely former Edexcel exam question comparing two pie charts). The link to the whole sheet is here but here is the part I designed:

"These pie charts show the car colours in two different car parks.

Say whether these statements are true, false or whether you cannot be sure from the given information:

a) The number of blue cars in the first car park is more than in the second car park.

b) The proportion of blue cars in the first car park is more than in the second car park.

c) The number of black cars in the first car park is more than in the second car park.

d) The proportion of red cars is the same in both car parks.

e) The largest proportion of cars in either car park are of white cars.

f) The smallest proportion of cars in either car park are of yellow cars.

g) The smallest number of cars in either car park are of yellow cars.

h) The largest number of cars in both car parks combined are red cars."

What I really like here is that pupils have to focus on whether or not there is enough information to answer the question, which puts a nice twist on the way we ask pupils about data and about maths in general. I think I will adapt this for different some other topics; I can see it being powerful to reinforce the idea of unknowns in algebra and whether you can get a numerical answer or not.