There is something called "cued speech" which is a system consisting of one hand synchronized with the natural mouth movements of spoken language. It's based on phonemes, which make up all spoken languages. It is not language-specific and can be adapted for use in virtually any spoken language. Adaptations are required because many languages use vowel sounds and/or consonant sounds that are not present for example in English. So you could use cued speech also to teach Spanish as a foreign language etc
Let's give an example. There's a deaf kid who want's to learn English. The teacher might use "cued speech" as method. By combining the shape of the mouth with the shape and position of the hand, you have a system that makes an efficient visual representation of all the sounds of the English language. A deaf child receiving the cues consistently learns to distinguish phonemes visually - in the same way that a hearing child does it auditorily - and is able to steadily and naturally acquire language.