DIRECTIONS TO STUDENTS 



Each observant person is constantly noting occurrences in nature which he would like to have 

 explained to him. A flying kite leads us to ask how it is made to fly. Boiling water in a kettle lifts 

 the lid which covers it, and we want to know what causes the lid to rise. The tender stem of a 

 plant pushes up through gravelly or hard-packed soil, crowding the pebbles and soil out of the way, 

 and we ask how the delicate shoot, still uninjured, can move such solid bodies. A colony of ants 

 makes its home in a field of corn ; the corn is soon retarded in its growth, and we want to know 

 what is taking place. A pupil visits a friend who is ill, and later the visitor may have the same 

 disease as that which affects the friend. What has occurred ? Many such questions concern our 

 daily lives, and we are more intelligent and more efficient persons when we can answer some of these 

 questions. 



There are two good ways of securing answers to our questions. One way is to ask persons who 

 know about these matters or to read what they may have written. The other way is to study the 

 occurrence by means of further observation and experiment, thus trying to make the occurrence itself 

 help to answer the question regarding it. It is the purpose of these outlines to use the latter method 

 in answering some important questions, as well as to lead to new questions. 



To secure the greatest good from an experiment it is necessary (1) to record the way in which 

 the experiment is performed ; (2) to state the facts shown by the experiment ; and (3) to explain 

 these facts, if an explanation can be made. When you have performed an experiment, write your 

 statement of these three points as clearly as if your notes were intended to be read by a person 

 who knows nothing about the experiment you are describing. Make diagrammatic outlines to repre- 

 sent the apparatus used, whenever such diagrams will help to make the process or results more clear. 

 In all cases make sure that your work is concise, neat, and clear in its presentation of the facts and 

 inferences from them. 



[xi] 



