From the Preface. The young teacher used to spend four or five years learning his professional work. Theory and practice went on side by side. The practical work has now been limited to one-half of a two-years' course, and theory has disappeared from the syllabus. Under these circumstances it is thought that many young teachers will more than ever require assistance to supplement their very brief and very empirical training. This little primer is a contribution towards that assistance, and it is hoped that it may be a real aid to those for whom it is written.