Henry Sweet was one of the founders of a new way of teaching foreign languages early in the twentieth century, a century littered with methodological alternatives to the grammar-translation approach. Sweet, like Gouin in France, believed that speech was more important than the written word and that languages should be taught primarily using the spoken word. The approach which subsequently developed was not a "direct method" as such since the oral approach assumed careful selection and gradation of target language input. It was strongly teacher-led, discouraged formal teaching of grammatical structures, preferring the notion that students would pick up rules from the skilled presentation and practice provided by the teacher.
The appraoch was also situational in that structures would be practised within a meaningful situational context, for example, family life.
Central to the approach is the use of repetition and question and answer in the classroom, along with contextual clues such as gesture, realia and visual aids. The IWB may have largely replaced flashcards and the OHP, but the principle is the same. Pair and group work are allowed for, but structured drilling should precede freer practice.
The approach is primarily structural rather than communicative, but there is clearly a strong communicative element to the traditional approach.
The principles of the oral approach are used, often instinctively, by teachers. who did not explicitly learn it. Nowadays, in this post-methods era, as it is sometimes refered to, many teachers adopt a pragmatic approach mixing elements of the oral, communicative, audio-lingual and grammar-translation approaches. This probably makes sense, particularly in view of the fact that students learn in different ways.
Does theoretical research support the use of the strict oral approach? Well, to the extent that natural acquisition requires considerable meaningful input in the target language, then yes. But there is no theoretical support for the view that conscious practice of structures and vocabulary leads to internalisation of rules. Children learning their mother tongue do not acquire language in this fashion. Experience suggests, however, that structured practice does lead to progress and that the oral approach works with many learners.