Use Of Exercises. Before beginning a piece of work, the student should read the text and the references, and should understand every step necessary to complete the model. It will be noticed that the sequence of exercises has been carefully worked out in connection with some of the models which include unusual or difficult features. Where this has been done, the progression should be followed carefully, as otherwise troublesome conditions may develop as the work progresses.

When a tool is used for the first time, the directions for its use should be carefully studied, and correct methods followed from the first.