[mesmark]

I'm not sure how much time you have but it might be beneficial to teach some phonics, but more so, some of the individual phonemes in English.

I assume they have already brushed over these in JHS or just through 6 years of education made some assumptions, but you could also work in images of the shape of the mouth and explain how the mouth is a musical instrument. Changes in shape create changes in sound. Most importantly, if they don't actually create the correct shapes, they can't make the correct sounds.