I just came across a post at The Linguist regarding whether or not beginning language students learning a foreign language need a teacher. Here is a snippet:
"What about beginners? Don't beginners need a teacher to explain the language, to teach the grammar? What if the new learner starts to speak incorrectly? How will the beginner figure out the meaning of even the easiest content items?
My answer! Beginners do not need teachers. Beginners and teachers have nothing to say to each other. They can only communicate in a language other than the target language.
The beginner needs to listen and read and build up vocabulary. The beginner needs to relate or link the new language to what he/she already knows - another language. So with the help of translation the beginner begins to form relations to concepts, usually in his/her own language, but eventually between sounds, words and phrases in the new language. The learner starts to discover the language, without relying on someone else's explanation.
By sticking to meaningful and interesting content, graded for difficulty and related to what the learner already knows, the long road of language learning can begin. The learner becomes increasingly familiar with a new language, first hand."