This textbook applies to high-school instruction the same general principles that have been applied so frequently and fruitfully to the consideration of elementary-school methods. It contains some of the materials used by the author in his classes in educational methods for prospective high-school teachers. Sometimes his classes contain both prospective elementary and high-school teachers. At such times, after a general principle of method has been discussed, applications are made to both elementary and high-school teaching, because practically every general principle of method does apply in both places. Inasmuch as the line between elementary and secondary (or adolescent) education should probably be drawn at about twelve or thirteen years of age, the illustrations given in this volume will apply in many cases to the seventh and eighth grades as well. It is the intention to issue a companion volume which will follow the same general lines as this one, but will draw its illustrations from the elementary grades proper; namely, from the kindergarten through the sixth grade.<br><br>The scientific basis for part of the discussion in the book is found in modem experimental psychology. This is particularly the case in the discussion of certain aspects of learning which have been subjected to extensive laboratory investigation, such as motor learning and practice. In other cases, where experimental data arc not available, I have relied on authoritative, analytical discussions such as Professor Dewey's "How We Think."