Unit 1c Book

Now that you know what a laser consists of, it is time to find out about its principle. To get to know how a laser works, complete the text in this task by choosing the correct option from the drop-down list.

After you finish and check your answers, focus again on the words you used to complete the text. You can see that some of them are sequencers indicating the order in which something happens, thus making the explanation more understandable. Some of them are expressions showing cause-effect relationships, which are crucial for explaining the technical principle. And, most importantly, the verb tense used to explain how a machine or a system works is the Present Simple tense. The reason is logical: when talking about a principle, you explain something which remains unchanged and is always true. If you think you need to revise the Present Simple tense, download its grammatical overview here.

Based on the tasks you have completed so far, how would you sum up what you have learned about an effective way of describing a machine or a principle? Well, it is a good idea to follow a kind of outline: after specifying the name of the machine/system and perhaps referring to its diagram, you should explain what the machine/system is for; in other words, what its function is. This information on the importance of the system/machine provides readers (or listeners) with a hook giving them a reason for either reading on or continuing to listen to your presentation.  After that, a list of its components should follow; if need be, supplemented with the location of the parts and the way they are attached or mounted. Once your reader/listener is aware of the machine/system parts, you can start talking about the technical principle of the machine/system, using the Present Simple tense, sequencers and appropriate cause-effect expressions. You can see the outline for describing a machine or a system here. If you feel that a simple outline is not enough for you, you can download its extended version here.