Most paragraphs, especially in technical fields, rely on solid topic sentences to convey their meaning clearly. Remember that topic sentences come in many forms and need not be the first sentences in paragraphs. However, if you have a paragraph that must be tidied up or you are composing a paragraph from scratch, offering a clear topic sentence as your opening statement is a good way to begin.
In technical writing, topic sentences take a number of forms. They often simply provide a general statement for the paragraph to support:
The role of coal in the hydrology of strip mines receives little attention in the literature. Most groundwater analyses of potential or current strip mines are simply concerned with . . .
Sometimes topic sentences simply kick off a list of examples:
There are obvious advantages associated with the real-time information that a measurement-while-drilling system supplies. The first advantage is . . .
Other topic sentences supply background or announce scenarios:
Ceramic tubes are now being used in the most aggressive environments. In industry . . .
Some topic sentences combine the listing of examples and background material:
Three points about the geologic activity of wind and the development of landscapes in dry lands are relevant here. First . . .
A simple, straightforward topic sentence is usually the best way to introduce general background, examples, scenarios, arguments, or even to establish a direct linkage to the preceding paragraph. Good writers use concrete and efficient topic sentences to control and unify their paragraphs. If you make it a practice to use the topic sentence as a tool to organize your thoughts, your paragraph content will fall into place more readily.
For more on topic sentences and some excellent practice exercises, visit the following sites: