Conditional clauses or If clauses are usually covered between pre-intermediate and intermediate levels. They are pretty easy to form, however, their meanings are a bit problematic for students. Students typically have difficulties in choosing the correct one when they need to use them. Besides, mastering the conditional clauses help students improving their language production. Especially, when they want to produce strong arguments, they'll use conditional clauses naturally.
In this grammar guide, conditional clauses are summarised in one-page PDF handout. Also, a special interest is given to the meaning of conditional sentences. The difference between the meanings of type zero, first, second and third are scrutinised together in a chain of questions which will help your students decide the correct If clause in usage.