Pronunciation can be a big challenge for many non-native English speakers. Certain English sounds simply don't exist in many of the world's languages. As a result, these students' mouth and tongue muscles have not learned how to make the shapes necessary for clear diction in English. Here's an idea that might help. Give students hand mirrors and have them study the shape their mouths and tongues make when they attempt difficult words and compare with a native English speaker. As students focus on and practice the correct mouth shape and tongue position, they should experience improvement in their pronunciation, empowering them as they are able to be understood by more and more people.