The difference is very subtle. Here, your teacher means EVERYONE. However, it would also have made sense if your teacher had said "Each of you" Normally "Every" and "each" are very very similar in meaning, but "each" further emphasises that out of a certain group of people/objects/animals, they ALL do the same thing. "Every" is almost always used, however, when speaking generally, and "each" only makes sense when the group of things is known EVERY dog is fluffy (all the dogs in the world are fluffy) EACH dog has a name (all the dogs in this room have a name) the difference is very subtle, so if you don't understand and you are not a native speaker, do not be discouraged!