Here's why this very high-level Academy Member missed out on a Band 7 for Task 1 Writing: there’s a problem with the overview.
This overview is absolutely crucial, and a lot of test-takers leave it out , or confuse it with the introduction.
This could lead to Band 5 for Task Achievement ("no clear overview").
What’s the difference between the introduction and the overview?
The introduction tells us what the graph is about (you just need to paraphrase the task).
Original task:
'The graph below shows the average monthly change in the prices of 3 metals during 2014.'
Student’s paraphrased introduction (good):
'The line chart illustrates the monthly average price fluctuations of three metals ( zinc, copper, nickel) throughout the year 2014 .'
The overview is a very brief summary of the data.
Imagine you're describing the results in one sentence to someone who cannot see the graph.
You do not need to include data in the overview.
Choose one or two noticeable trends or changes.
Write 'Overall,...' and put it right after the introduction.
Be specific but not too detailed.
The student's example above is too general.
A better overview might be this example of a 'good answer' (Band 6) from the Cambridge Practice Test:
This example from Anh shows you how you can use a complex sentence (with 'whereas')
*A compound sentence joins simple sentences together, using words like and, but or so.
**A complex sentence joins clauses together using words like after, because, who, whenever and whereas.