1. A method for instructing a user how to operate a word recognition system which recognizes which word, from an active vocabulary of possible words, appears to most closely match each of a plurality of user generated signals, including how to operate that system to perform a recognition task which uses an active vocabulary of N or more words, said method comprising the steps of: defining a state machine having a plurality of states and a set of one or more allowed response words for each such state and associating with each such response word a new state which the state machine will enter in response to the recognition of a user generated signal as that response word, with the number of allowed response words associated with each such state being substantially less than N; when said state machine is in each of a first set of said states, sending a user one or more instruction messages associated with that state to teach the user how to use the recognition system; when said state machine is in states of a second set of said states, presenting the user with recognition exercises which simulate use of the recognition system for said task which uses a vocabulary of N or more words, but which prompts the user to produce a user generated signal representing a word corresponding to one of the smaller number of response words allowed for the current state of said second set; when said state machine is in each of said states, using an automatic signal matching means to score closeness of matches between a user generated signal and models for each of a plurality of words, including at least the response words allowed for that state; and responding to the scores produced by said matching means to select which of the response words allowed for the current state probably corresponds to the user generated signal for that state and advancing the state machine to the state associated with that selected response word; whereby the user can progress through a succession of said states, to receive a corresponding succession of instruction messages and exercises, selected in response to the scoring of his or her user generate signals against allowed response words.