1. A teaching machine, particularly, for teaching foreign languages, comprising: a housing; an algorithmic-problem introducing unit located in said housing; a machine control unit located in said housing and operatively connected to said algorithmic-problem introducing unit; a set of coded programs corresponding to the introduced algorithmic problems and incorporated into said machine control unit; programming switches of said machine control unit electrically connected to said set of coded programs; an answer selection unit disposed in said housing and electrically connected to said algorithmic-problem introducing unit; a signalling unit located in said housing and electrically connected to said answer selection unit and to said algorithmic-problem introducing unit; a plurality of switching elements of said answer selection unit; a replaceable program frame of said answer selection unit adapted to be replaced when the code of a program is varied; a plurality of electric plug contacts of said replaceable program frame, said electric plug contacts differing in length so as to provide electrical means for the operable choice of one of the coded programs of said control unit; a plurality of sockets for said electric plug contacts, said sockets being electrically connected to said programming switches of said machine control unit, the signal output from said sockets being operatively connected to said answer selection unit; a plurality of discrete areas in said replaceable program frame; a code panel adapted to be laid under said replaceable program frame; a plurality of language elements recorded on said code panel and adapted to form the answers to algorithmic problems; said language elements located in said discrete areas of said replaceable program frame opposite said respective switching elements.
1. A teaching machine, particularly, for teaching foreign languages, comprising: a housing; an algorithmic-problem introducing unit located in said housing; a machine control unit located in said housing and operatively connected to said algorithmic-problem introducing unit; a set of coded programs corresponding to the introduced algorithmic problems and incorporated into said machine control unit; programming switches of said machine control unit electrically connected to said set of coded programs; an answer selection unit disposed in said housing and electrically connected to said algorithmic-problem introducing unit; a signalling unit located in said housing and electrically connected to said answer selection unit and to said algorithmic-problem introducing unit; a plurality of switching elements of said answer selection unit; a replaceable program frame of said answer selection unit adapted to be replaced when the code of a program is varied; a plurality of electric plug contacts of said replaceable program frame, said electric plug contacts differing in length so as to provide electrical means for the operable choice of one of the coded programs of said control unit; a plurality of sockets for said electric plug contacts, said sockets being electrically connected to said programming switches of said machine control unit, the signal output from said sockets being operatively connected to said answer selection unit; a plurality of discrete areas in said replaceable program frame; a code panel adapted to be laid under said replaceable program frame; a plurality of language elements recorded on said code panel and adapted to form the answers to algorithmic problems; said language elements located in said discrete areas of said replaceable program frame opposite said respective switching elements. 5. A teaching machine as claimed in claim 1, wherein said machine control unit has means for automatically advancing a teaching program through successive incremental steps, said means being electrically connected to said plug contacts of said replaceable program frame.