Our goal in teaching pronunciation is not to rid learners of their own accents and distinctive ways of speaking. However, clarity in communication should be the number one goal and learners accents can sometimes be an obstacle to comprehensibility.
A very common problem which non-native speakers may have is that phonological elements of English might not exist in their own native language and so are hard to reproduce, or the letter of the alphabet used has a different sound leading to L1 interference.
A common way to make students aware of these possible problems and set them on the road to correcting them is with the use of minimal pairs. These are pairs of similar words which have different meanings but which a speaker might have problems vocally differentiating. For example, German speaker often have a problem distinguishing the words bad and bed due to the absence of the A vowel sound in their own language. Similarly a native speaker of Spanish might have problems distinguishing the words yolk and joke because the letter J has the same sound as the letter Y in the Spanish alphabet. Therefore, for this activity try and find groups and pairs of words that your students tend to have a particular problem with.
A google search for minimal pairs + language should give you a run down of the kind of pronunciation problems that your learners might have, and EnglishClub has a great directory of minimal pairs for each set of problem sounds.
Choose four or five similar minimal pairs and write them on the board in two columns, for example:
Say one of the words from the board and have students tell you whether the word is from column 1 or column 2. Repeat this a few times and then have students do the same in pairs. Repeat this stage for each minimal pair which you want to review and practise.
You will need to create a set of cards (twenty or more) that contain examples of minimal pairs that you wish to practise (example set). Each student will need their own set. Put students in pairs, each pair will need to set up some kind of barrier between them so they can’t see which cards the other studens has laid on their side of the desk. A course book held up by one of the students should suffice.
Student A must now choose eight cards from their set and lay them out on the table behind the barrier, the student then tells student B each card which he/she has laid and student B lays the card which they think they heard. Student A can only repeat the word a maximum of three times before moving on. After student B has put down his/her 8 cards, the barrier is removed to see whether the student have managed to create sets of matching cards. Rotate the pairs so that students are exposed to different speakers.
As a bonus activity you could have pairs or groups of students make up a story using the words from the cards.