This approach is student-centered: it is not just the teacher telling the students what grammar rules are. They are actually discovering information for themselves.
There may be such tasks as:
Search the text and see how many examples of If-clauses you can find. Do they mean time or condition?
The text is used not only for comprehension, but also to make students see the meaning and the use of new language.
Another example:
Read through a text and find the two uses of the modal verb “can” expressing possibility.
Such tasks are aimed at making students be aware of a new piece of language. Matching techniques are aimed at getting the students to work things out for themselves and help them to discover correct fact about English grammar.
For example: Students are asked to do a matching exercise comparing the use of “unless” and “if” , “since” and “for” , “till” and “until”. Another way of getting students to discover new grammar is to ask them to concentrate on its use in a text. Students are personally involved in the acquisition of grammatical knowledge.
As to the students’ problem-solving activity, they should be encouraged to talk about grammar, to analyze its properties and to decide what is wrong and what is right.
Task: List your most common mistakes in grammar. What would you like to do to identify your mistakes and put them right?
The use of discovery techniques can be highly motivating and extremely helpful for the students’ understanding of English grammar.