It is not intended that the lessons or definitions are to be learned verbatim, any more than it is intended that the examples given are to be memorized; both are there for the purpose of showing the pupil the reason for, and the application of, the processes, and the exercises are there to give him practice and to test his knowledge of what he has learned. The exercises form a continuous review of what has been learned, but further review work is given at regular intervals. The series consists of Three Books and Teacher's Manuals, as follows: Primary Lessons. Parts I and II. (Teacher's Elementary Lessons....Parts III and IV. (With Man- Intermediate Lessons... Parts V and VI. (With Manual for the Teacher.) Advanced Lessons. .Parts VII and VIII. (With The first two parts are so arranged in the Teacher's Manual that the lessons and exercises can be given largely as games, play work, number stories in language work, etc., all used more or less incidentally, till the child is gradually prepared for work requiring an increasing degree of conscious effort. The work contained in each of the eight parts is that which is usually taught in the corresponding grade, and it is recommended that this routine be followed. However, special provision has been made for such variations in the grading as are required in some localities, by means of a series of notes in the Teacher's Manuals which enable the teacher to follow either method with equal facility. The authors wish to express their deep appreciation to Mr. E. C. Hinkle and Mr. J. R. Clark, both of the Department of Mathematics, Chicago Normal College, for their critical examination of the manuscript and their valuable suggestions for its improvement. 28. COMPUTING INTEREST WHEN THERE ARE PARTIAL PAYMENTS. 109 |