Over the past century many different methods or approaches have been applied to the teaching and learning of foreign languages. Since the 1960s, for example there has been a shift from approaches that concentrate on learning grammar, vocabulary and on translation, to approaches the emphasise communication, especially speaking. The same thing also happened in the second half of the 19th century.
Much research has been undertaken into language learning and teaching, but as far as I can discover, no single approach or method has been found to work significantly better than any other, in spite of claims to the contrary by the inventors, founders and promoters of particular methods and approaches.
Moreover, each new development in technology, whether it be the phonograph, radio, television, computer or internet, is expected to transform the way people learn languages. However this doesn't necessarily happen.