20. Apparatus according to claim 15 further characterized in that said letter combinations are word roots, and further comprising: temporary memory storage means, correctness and incorrectness indicators, console means having manually actuable switches for generating electronic signals for different alphabet letters, and further characterized in that said logic processing means is adapted to ascertain valid language suffix letter combinations which form language words when prefaced by the word root most recently selected by said word selection means, and means for transferring said suffix letter combinations to said temporary memory storage means, and to draw said suffix letter combinations from said temporary memory storage means upon subsequent receipt of letter combinations manually entered into said console means for comparision therewith and comparator means connected to said logic processing means for receiving said manually entered letter combinations from said console means and the suffix letter combinations stored in said temporary memory storage means in association with the most recently selected word root, and for providing an output indication of comparison results to one of said correctness and incorrectness indicators
20. Apparatus according to claim 15 further characterized in that said letter combinations are word roots, and further comprising: temporary memory storage means, correctness and incorrectness indicators, console means having manually actuable switches for generating electronic signals for different alphabet letters, and further characterized in that said logic processing means is adapted to ascertain valid language suffix letter combinations which form language words when prefaced by the word root most recently selected by said word selection means, and means for transferring said suffix letter combinations to said temporary memory storage means, and to draw said suffix letter combinations from said temporary memory storage means upon subsequent receipt of letter combinations manually entered into said console means for comparision therewith and comparator means connected to said logic processing means for receiving said manually entered letter combinations from said console means and the suffix letter combinations stored in said temporary memory storage means in association with the most recently selected word root, and for providing an output indication of comparison results to one of said correctness and incorrectness indicators 21. Apparatus according to claim 20 further characterized in that said logic processing means is adapted to differentiate between those suffix letter combinations theretofor correctly manually entered in association with the word root most recently selected and those remaining unselected and to provide an output indication to said visual display means signifying that further suffix letter combinations remain unselected for the most recently selected word root until all of them have been manually entered and received.