5. A problem may be suggested, and a few days allowed for the pupils to think out a means of solution. If they invent and make their own apparatus, so much the better. 6. Whenever possible, the experiment should be applied to some natural phenomenon or everyday occurrence. CORRELATIONS OF PHYSICAL SCIENCE PHASE Geography.--The value of Physical Science in the Elementary School is largely due to the light it throws on geographical data. Numerous examples will appear in the succeeding pages. Hygiene.--Experiments in carbon dioxide, oxygen, air, water, sound, and light, are absolutely necessary, if the children are to grasp with any degree of clearness the principles of respiration and ventilation, and the phenomena of hearing and seeing. Manual Training.--Many pieces of apparatus may be made by the boys in their work with wood or iron. Some of the elementary principles of chemistry enable the girls to do their cooking intelligently. A knowledge of some of the principles of machines will help the pupils to understand the tools they may use in any employment. Drawing.--Careful drawing of the apparatus used helps to fix the experiment in the mind and at the same time gives practice in art. Composition.--Pupils must have ideas before they can write. The description of the experiment will make a good composition exercise, oral or written. LIST OF REFERENCE BOOKS AND BULLETINS GARDEN AND PLANT STUDY Bulletins of the Ontario Department of Agriculture, Toronto. Bulletins of the Dominion Department of Agriculture, Ottawa. Improvement of School Grounds. Department of Education, Toronto. Atkinson. First Studies of Plant Life. Ginn & Co. 60 cents. Bailey. Manual of Gardening. Macmillan Co. $2.00. Blanchan. Nature's Garden. Doubleday Co. $2.00. Comstock, A. M. Handbook of Nature Study. Comstock Pub. Co. $3.25. Gray. Field, Forest, and Garden Botany. Amer. Book Co. $1.40. Green, Louise. Among School Gardens. Charities Pub. Co. $1.25. Hodge. Nature Study and Life. Ginn & Co. $1.50. Holtz. Nature Study. Scribners' Sons. $1.50. Jackson and Dougherty. Agriculture through the Laboratory and School Garden. Judd. $1.50. James. Agriculture. Appleton & Co. 80 cents. Keeler. Our Native Trees. Scribners' Sons. $2.00. Osterhout. Experiments with Plants. Macmillan Co. $1.50. Parsons. How to Plan the Home Grounds. Doubleday Co. $1.00. Sergeant. Corn Plants. Houghton, Mifflin Co. 75 cents. PHYSICAL SCIENCE Miller. Minerals and How They Occur. The Copp, Clark Co. $1.50. Milliken and Gale. First Course in Physics. Ginn & Co. $2.00. Newman. Laboratory Exercises. Ginn & Co. 10c. each. Remsen. College Chemistry. Am. Pub. Co. $2.50. Simmons and Syenhouse. Science of Common Life. The Macmillan Company, $1.00. Woodhull. Home-made Apparatus. High School Text-books. ANIMAL STUDY Bulletin No. 52. Dominion Department of Agriculture, Ottawa. Bulletin No. 134. Ontario Department of Agriculture, Toronto.