Conditional sentences can be confusing for ESL students.
After all, these sentences are talking about imaginary situations and imaginary outcomes. How does a person get tangible lessons into the classroom when the topic is imaginary? One particular area of confusion many ESL students (and teachers) struggle with is the difference between “if” and “unless”. On first glance, the two seem very similar, opposite in fact, but in actuality each has very specific circumstances under which it should be used. If you want to make sure your students are clear on the difference between if and unless, follow these five simple steps for distinguishing between the two.
The Exception Is the Rule: Help Your Students Distinguish between IF and UNLESS
Be Comfortable with “If” Conditionals
Obviously, before your students can distinguish between if and unless in conditional statements, they will have to understand how to use if-clauses. Conditionals are used to talk about a situation, event, or reaction that are directly related to another situation, event, or reaction. Sometimes these events are real, and other times they are hypothetical, and the outcomes depend on certain circumstances. If he comes, I will be upset. (I don’t want him to come, and I will be upset if I see him there.) English has four basic types of conditional statements, often referred to as zero, first, second, and third. For a general review of conditionals, see Are your students suffering from conditional confusion? Try these simple activities for practicing conditional structures. Each conditional statement has an if-clause (the hypothetical or yet to be circumstance) and a result clause (what will happen if the circumstance in the first clause happens). The if-clause states the specific circumstances that will bring about the result in the second clause.
You can find exercises on conditional sentences in just about any grammar book or on more websites than you will ever need. The most important part of these exercises is that students understand the two different functions of the two different clauses in the conditional sentence.
Negative “If” Conditionals
Once your students understand the general construction of conditional statements, it’s time to add a negative into the mix. Negative conditional statements again express a certain set of circumstances as well as a result of those circumstances. They are the same as positive conditional sentences in structure except for the negation of the verb in the if-clause. If he doesn’t come, I will be upset. (I want him to come. If I do not see him there I will be upset.) Negative conditional statements can be used to talk about any circumstances that may or may not happen, to express any typical results that would happen if the circumstances in the negative if-clause are met.
To practice negative if-clauses, have students take the sentences from the first exercise and make the if-clause negative. What do they have to do to the result clause to keep the meaning of the sentence consistent?
Unless = If…Not
The easiest way to explain “unless” is to say it is the equivalent of a negative if-clause. If I do NOT win the lottery, I will not be able to buy a car. Unless I win the lottery, I will not be able to buy a car. This explanation is a good introduction to unless-clauses, but it is not the whole story. For example, the following two sentences are not equivalents. If I don’t win the contest, I will be disappointed. Unless I win the contest, I will be disappointed. The latter sentence sounds strange, as if winning the contest is the only thing that will keep that person from being disappointed, which brings us to the exception to the unless-rule.
The Exception to the Rule
Unless-clauses are not used for ordinary cause and effect relationships. By using “unless” in a clause, the speaker is implying that the circumstances in the unless-clause are not very likely. The event in that clause is the ONLY circumstance under which the result clause will happen. In the above example, many circumstances might prevent the speaker from being disappointed, one of which may be winning the contest, but the general state of that person is probably not to be disappointed. The event in the result clause, therefore, is what we expect to happen. It is the normal outcome, the most likely result, and so unless is not the appropriate choice for that sentence. In this case, the appropriate sentence is this: If I don’t win the contest, I will be disappointed. Therefore, speakers should not use “unless” for an if-clause that is likely to happen.
If Not or Unless
Your students will need practice to determine which choice is the best one for a given sentence: if not or unless. To do so, encourage your students to ask themselves the following questions. Is the event in the result clause almost always true? Is the if/unless-clause unlikely to happen? Is the circumstance in the if/unless clause the one set of circumstances which would prevent that result from happening? If the answer to these questions is yes, the correct choice is “unless”. Also ask these questions. Is the result clause something that is true? Is the if/unless-clause something that might change the result clause? Is that event or are those circumstances something that is likely? If the answer to these questions is yes, “if…not” is the better choice. In short, if the circumstance in the if/unless clause is likely to happen, if…not is the right choice. If it is not likely to happen, unless is the best choice.
Give your students some practice distinguishing between if…not and unless in conditional sentences with examples such as the following. Have students decide which sentence is the better choice in the following pairs. (Correct answers are in italics.)
- If you don’t have your book, you cannot do your homework.
- Unless you have your book, you cannot do your homework.
- If he does not wear a tie, he will be dressed appropriately for the event.
- Unless he wears a tie, he will be dressed appropriately for the event.
Distinguishing between correct use of if and unless will take some practice for your ESL students. If you are patient and walk them through the logic of the choices, they will eventually be successful in distinguishing between the two structures. Take it one step at a time and all of you will get there.
Do your students struggle with the difference between if and unless?
How do you help them through that struggle?