Computerized spelling and grammatical correctors are nowadays systematically built-in tools in word processing software. The pupils and their teachers are brought to use it without a clear vision of its didactical implications. This study measures the effectiveness of a computerized corrector on pupil’s dictation (5th primary class). Under automatic process; it "corrects" 30% of the errors. This is an encouraging result. An improvement of the algorithms and specific didactics for this public should make a helpful tool for the training of writing at school, impossible to circumvent in the future, like the calculator became in mathematics.