Modified Dec. 20, 2013
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Model Answer, Cambridge Practice IELTS Tests, Book 8, Test 3, Task 1
The two diagrams, “Cement Production” and “Concrete Production” show two distinctly different processes, involving several contrasts, although the end-product of the cement production process provides one of the input ingredients for concrete production.
More specifically, cement production requires four pieces of equipment, with each piece of equipment being used for one of the four steps in the production process, while only a concrete mixer is needed to make concrete, in a simple mixing process. Furthermore, cement is produced by combining only two ingredients, limestone and clay, while concrete production combines four ingredients, viz., cement, water, sand and gravel, input in specific volume ratios of 15:10:25:50, respectively. Finally, the more complex cement-making process involves reducing the size of the input ingredients by crushing and grinding and the use of heat while concrete-making involves neither of these.
Considering each process individually; cement production begins with the simultaneous crushing of limestone and clay to produce a powder, which is then mixed more thoroughly, heated in a rotating heater and then ground to a fine powder, which is the final product, cement. On the other hand, the diagram for concrete production shows only one step, i.e., the four ingredients, cement, water, sand and gravel being simultaneously added to a continuously rotating concrete mixer, to produce the final product, concrete.
Word count = 215
I think the first sentence (= the first paragraph) here is good enough to focus the reader’s attention without re-wording the words from the question. I like the idea of referring the reader to a diagram or graph etc. by simply giving the title of the diagram or graph etc. This is what is done in a report in real life that consists of a summary of a graph or diagram.
I included an item, “volume ratios” which is not given in the data. That is true but perhaps it is dangerous to do since the ratios are not stated as “volume” – they could be weight ratios but weight ratios are not usually stated as percentages, while volume ratios are. So maybe the word “volume” is best not used here. Personally, I would not penalize a candidate for that since not all knowledge or information is ever given in data – there is always some presumption of further knowledge or understanding.
Although the ratios are obvious, I think the examiner wants to see at least some specific numbers transferred from the diagram (or a graph) to the essay so I inserted them (after I was not going to do that, initially.)
Overall, I think the main point of this particular Task 1 is to contrast the differences between the two processes – describing each process is important but secondary in importance to the comparison of the two. That’s why the first 2 paragraphs focus on comparing and only one paragraph is used to outline the individual processes. (That is, the first 135 words, compared to the last 80 words.)