They also have a lot of trouble with the “th” cluster, as this does not appear in the Thai language, and in Thailand, it is considered very impolite to stick out one's tongue (which is what they feel this cluster requires). Thais therefore try to make the “th” sound with their tongues inside their mouths. The best way to deal with such problems is to know how the sounds actually are made by the mouth and tongue and to be ready to explain and demonstrate this (hopefully, without causing too much laugher in the fun-loving students)!