Chapter II: Preface

A collection of about 2000 questions asked by children forms the foundation on which this book is built. Rather than decide what it is that children ought to know, or what knowledge could best be fitted into some educational theory, an attempt was made to find out what children want to know. The obvious way to discover this was to let them ask questions.

The questions collected were asked by several hundred children in the upper elementary grades, over a period of a year and a half. They were then sorted and classified according to the scientific principles needed in order to answer them. These principles constitute the skeleton of this course. The questions gave a very fair indication of the parts of science in which children are most interested. Physics, in simple, qualitative form,--not mathematical physics, of course,--comes first; astronomy next; chemistry, geology, and certain forms of physical geography (weather, volcanoes, earthquakes, etc.) come third; biology, with physiology and hygiene, is a close fourth; and nature study, in the ordinary school sense of the term, comes in hardly at all.

The chapter headings of this book might indicate that the course has to do with physics and chemistry only. This is because general physical and chemical principles form a unifying and inclusive matrix for the mass of applications. But the examples and descriptions throughout the book include physical geography and the life sciences. Descriptive astronomy and geology have, however, been omitted. These two subjects can be best grasped in a reading course and field trips, and they have been incorporated in separate books.

The best method of presenting the principles to the children was the next problem. The study of the questions asked had shown that the children's interests were centered in the explanation of a wide variety of familiar facts in the world about them. It seemed evident, therefore, that a presentation of the principles that would answer the questions asked would be most interesting to the child. Experience with many different classes had shown that it is not necessary to subordinate these explanations of what children really wish to know to other methods of instruction of doubtful interest value.

Obviously the quantitative methods of the high school and college were unsuitable for pupils of this age. We want children to be attracted to science, not repelled by it. The assumption that scientific method can be taught to children by making them perform uninteresting, quantitative experiments in an effort to get a result that will tally with that given in the textbook is so palpably unfounded that it is scarcely necessary to prove its failure by pointing to the very unscientific product of most of our high school science laboratories.

After a good deal of experimenting with children in a number of science classes, the method followed in this book was developed. Briefly, it is as follows:

At the head of each section are several of the questions which, in part, prompted the writing of the section. The purpose of these is to let the children know definitely what their goal is when they begin a section. The fact that the questions had their origin in the minds of children gives reasonable assurance that they will to some extent appeal to children. These questions in effect state the problems which the section helps to solve.

Following the questions are some introductory paragraphs for arousing interest in the problem at hand,--for motivating the child further. These paragraphs are frequently a narrative description containing a good many dramatic elements, and are written in conversational style. The purpose is to awaken the child's imagination and to make clear the intimate part which the principle under consideration plays in his own life. When a principle is universal, like gravity, it is best brought out by imagining what would happen if it ceased to exist. If a principle is particular to certain substances, like elasticity, it sometimes can be brought out vividly by imagining what would happen if it were universal. Contrast is essential to consciousness. To contrast a condition that is very common with an imagined condition that is different brings the former into vivid consciousness. Incidentally, it arouses real interest. The story-like introduction to many sections is not a sugar coating to make the child swallow a bitter pill. It is a psychologically sound method of bringing out the essential and dramatic features of a principle which is in itself interesting, once the child has grasped it.

Another means for motivating the work in certain cases consists in first doing a dramatic experiment that will arouse the pupil's interest and curiosity. Still another consists in merely calling the child's attention to the practical value of the principle.

Following these various means for getting the pupil's interest, there are usually some experiments designed to help him solve his problem. The experiments are made as simple and interesting as possible. They usually require very inexpensive apparatus and are chosen or invented both for their interest value and their content value.

With an explanation of the experiments and the questions that arise, a principle is made clear. Then the pupil is given an opportunity to apply the principle in making intelligible some common fact, if the principle has only intelligence value; or he is asked to apply the principle to the solution of a practical problem where the principle also has utility value.

The "inference exercises" which follow each section after the first two consist of statements of well-known facts explainable in terms of some of the principles which precede them. They involve a constant review of the work which has gone before, a review which nevertheless is new work--they review the principles by giving them new applications. Furthermore, they give the pupil very definite training in explaining the common things around him.

For four years a mimeographed edition of this book has been used in the elementary department of the San Francisco State Normal School. During that time various normal students have tried it in public school classes in and around San Francisco and Oakland, and it has recently been used in Winnetka, Illinois. It has been twice revised throughout in response to needs shown by this use.

The book has proved itself adaptable to either an individual system of instruction or the usual class methods.

TO THE TEACHER

Do not test the children on the narrative description which introduces most sections, nor require them to recite on it. It is there merely to arouse their interest, and that is likely to be checked if they think it is a lesson to be learned. It is not at all necessary for them to know everything in the introductory parts of each section. If the children are interested, they will remember what is valuable to them; if they are not, do not prolong the agony. The questions which accompany and follow the experiments, the applications or required explanations at the ends of the sections, and the extensive inference exercises, form an ample test of the child's grasp of the principles under discussion.

It is not necessary to have the children write up their experiments. The experiments are a means to an end. The end is the application of the principles to everyday facts. If the children can make these applications, it does not matter how much of the actual experiments they remember.

If possible, the experiments should be done by the pupils individually or in couples, in a school laboratory. Where this cannot be done, almost all the experiments can be demonstrated from the teacher's desk if electricity, water, and gas are to be had. Alcohol lamps can be substituted for gas, but they are less satisfactory.

It is a good plan to have pupils report additional exemplifications of each principle from their home or play life, and in a quick oral review to let the rest of the class name the principles back of each example.

This course is so arranged that it can be used according to the regular class system of instruction, or according to the individual system where each child does his own work at his natural rate of progress. The children can carry on the work with almost no assistance from the teacher, if provision is made for their doing the experiments themselves and for their writing the answers to the inference exercises. When the individual system is used, the children may write the inference exercises, or they may use them as a basis for study and recite only a few to the teacher by way of test. In the elementary department of the San Francisco State Normal School, where the individual system is used, the latter method is in operation. The teacher has a card for each pupil, each card containing a mimeographed list of the principles, with a blank after each. Whenever a pupil correctly explains an example, a figure 1 is placed in the blank following that principle; when he misapplies a principle, or fails to apply it, an _x_ is placed after it. When there are four successive 1's after any principle, the teacher no longer includes that principle in testing that child. In this way the number of inference exercises on which she hears any one individual recite is greatly reduced. This plan would probably have to be altered in order to adapt it to particular conditions.

The Socratic method can be employed to great advantage in handling difficult inferences. The children discuss in class the principle under which an inference comes, and the teacher guides the discussion, when necessary, by skillfully placed questions designed to bring the essential problems into relief.[1]

[Footnote 1: At the California State Normal School in San Francisco, this course in general science is usually preceded by one in "introductory science."]

The chapters and sections in this book are not of even length. In order to preserve the unity of subject matter, it was felt desirable to divide the book according to subjects rather than according to daily lessons. The varying lengths of recitation periods in different schools, and the adaptation of the course to individual instruction as well as to class work, also made a division into lessons impracticable. Each teacher will soon discover about how much matter her class, if she uses the class method, can take each day. Probably the average section will require about 2 days to cover; the longest sections, 5 days. The entire course should easily be covered in one year with recitations of about 25 minutes daily. Two 50-minute periods a week give a better division of time and also ought to finish the course in a year. Under the individual system, the slowest diligent children finish in 7 or 8 school months, working 4 half-hours weekly. The fastest do it in about one third that time.

Upon receipt of 20 cents, the publishers will send a manual prepared by the author, containing full instructions as to the organization and equipment of the laboratory or demonstration desk, complete lists of apparatus and material needed, and directions for the construction of a chemical laboratory.

The latter is a laboratory course in which the children are
turned loose among all sorts of interesting materials and
apparatus,--kaleidoscope, microscope, electric bell, toy
motor, chemicals that effervesce or change color when put
together, soft glass tubing to mold and blow, etc. The teacher
demonstrates various experiments from time to time to show the
children what can be done with these things, but the children
are left free to investigate to their heart's content. There
is no teaching in this introductory course other than brief
answers to questions. The astronomy and geology reading
usually accompany the work in introductory science.

ACKNOWLEDGMENTS

To Frederic Burk, president of the San Francisco State Normal School, I am most under obligation in connection with the preparation of this book. His ideas inspired it, and his dynamic criticism did much toward shaping it. My wife, Heluiz Chandler Washburne, gave invaluable help throughout the work, especially in the present revision of the course. One of my co-workers on the Normal School faculty, Miss Louise Mohr, rendered much assistance in the classification and selection of inferences. Miss Beatrice Harper assisted in the preparation of the tables of supplies and apparatus, published in the manual to accompany this book. And I wish to thank the children of the Normal School for their patience and cooperation in posing for the photographs. The photographs are by Joseph Marron.

CONTENTS

CHAPTER PAGE

1. GRAVITATION 1

1. A real place where things weigh nothing and
where there is no up or down 1

2. "Water seeks its own level" 6

3. The sea of compressed air in which we live:
Air pressure 10

4. Sinking and floating: Displacement 23

5. How things are kept from toppling over:
Stability 29

2. MOLECULAR ATTRACTION 36

6. How liquids are absorbed: Capillary attraction 36

7. How things stick to one another: Adhesion 41

8. The force that makes a thing hold together:
Cohesion 44

9. Friction 49

3. CONSERVATION OF ENERGY 57

10. Levers 57

11. Inertia 66

12. Centrifugal force 72

13. Action and reaction 77

14. Elasticity 82

4. HEAT 88

15. Heat makes things expand 88

16. Cooling from expansion 94

17. Freezing and melting 96

18. Evaporation 100

19. Boiling and condensing 107

20. Conduction of heat and convection 116

5. RADIANT HEAT AND LIGHT 122

21. How heat gets here from the sun; why things
glow when they become very hot 122

22. Reflection 129

23. The bending of light: Refraction 136

24. Focus 142

25. Magnification 150

26. Scattering of light: Diffusion of light 158

27. Color 161

6. SOUND 174

28. What sound is 174

29. Echoes 183

30. Pitch 185

7. MAGNETISM AND ELECTRICITY 190

31. Magnets; the compass 190

32. Static electricity 196

8. ELECTRICITY 203

33. Making electricity flow 203

34. Conduction of electricity 213

35. Complete circuits 219

36. Grounded circuits 225

37. Resistance 229

38. The electric arc 233

39. Short circuits and fuses 240

40. Electromagnets 247

9. MINGLING OF MOLECULES 259

41. Solutions and emulsions 259

42. Crystals 265

43. Diffusion 268

44. Clouds, rain, and dew: Humidity 274

45. Softening due to oil or water 290

10. CHEMICAL CHANGE AND ENERGY 293

46. What things are made of: Elements 293

47. Burning: Oxidation 312

48. Chemical change caused by heat 323

49. Chemical change caused by light 326

50. Chemical change caused by electricity 335

51. Chemical change releases energy 340

52. Explosions 342

11. SOLUTION AND CHEMICAL ACTION 349

53. Chemical change helped by solution 349

54. Acids 351

55. Bases 355

56. Neutralization 360

57. Effervescence 365

12. ANALYSIS 370

58. Analysis 370

APPENDIXES:

A. The Electrical Apparatus 379

B. Construction of the Cigar-box Telegraph 381

INDEX 383

COMMON SCIENCE