Here is a lesson that I have written over at IELTS in Taiwan.
https://ieltsintaiwan.wordpress.com/2015/12/08/ielts-writing-task-1-how-to-use
-comparatives-public-transport-in-europe/
It's called How to Use Comparatives.
In the exan, you are told to "make comparisons where relevant". But most stude
nts struggle to compare the data in the various Task-1 graphics! In this lesso
n, I've used a pie chart of public transport use in Europe as an example, and
I show how to make sentences using the various ways to compare.
Please click over to see how it is done.
And please join my Facebook group to discuss this and other things.
https://facebook.com/groups/767699863305697/