In foreign language teaching, the sandwich technique is the oral insertion of an idiomatic translation in the mother tongue between an unknown phrase in the learned language and its repetition, in order to convey meaning as rapidly and completely as possible.
The mother tongue equivalent can be given almost as an aside, with a slight break in the flow of speech to mark it as an intruder.
For example, a German teacher of English might engage in the following exchange with the students: With this technique meaning is conveyed quickly, interference from the mother tongue (or negative transfer) is avoided and students can fully concentrate on repeating the foreign phrase correctly.
The teacher can also use richer and more authentic texts sooner, for instance in telling stories: Mother tongue equivalents are always and immediately given in contexts, which is a far cry from isolated vocabulary equations.
By using the mother tongue skillfully, it is argued[citation needed], eventually whole lessons in the foreign language only can be given.