http://www.ck12.org Chapter 1. Introduction to Chemistry
FIGURE 1.
The steps of the scientific method are
easily represented using a flowchart.Making a Hypothesis
Ahypothesisis a testable conjecture that proposes an answer to the question. A hypothesis for the nonfunctioning
lamp could be that the light bulb is burned out. In order to be a valid hypothesis, it must be possible to test it.
Testing the Hypothesis and Analyzing Results
The light bulb could be easily removed and replaced with another one. If the new light bulb works, then the original
hypothesis is confirmed. However, if the lamp still does not work even when the light bulb has been replaced, the
hypothesis is now in question. Further experiments with more light bulbs could be done. Eventually, if the lamp
continues not to work, the original hypothesis must be discarded. At this point, the scientist may decide to either
make a slight change in the hypothesis or abandon the experiment entirely. Perhaps the change could be that there
is a problem with the switch for the lamp that is preventing it from working. A new set of experiments could be
performed to determine if the original switch was responsible for the lamp not working.
The lamp example oversimplifies the usual process in a real scientific experiment. In most experiments, multiple
experimental groups are created in order to test the effect of one variable on another. For example, suppose that
you wanted to know how elevated air temperature affects the germination rate of a certain type of bean seed. You
would set up multiple pots planted in identical fashion with the same bean seeds. You would establish experimental
constants such as the amount of water and the amount of light that each planting would receive. Theindependent
variablein an experiment is the variable that is changed during an experiment. In this case, the temperature is the
independent variable. You would figure out a way to place each of the experimental groups at a different elevated
temperature. One planting would be left at room temperature. This is called the control group. Acontrol group
is a group that experiences the same conditions as the experimental groups with the exception of the variable that
is being tested. The bean plantings would be observed at regular intervals, perhaps every 12 hours. Data would be
collected as to how many bean seeds germinated in each planting and when germination took place. Thedependent
variablein an experiment is the variable that is observed during an experiment. In this experiment, germination of
the bean seeds is the dependent variable.
In order to be confident about the results of an experiment, it needs to be repeatable. Professional scientists normally
repeat experiments many times before they make their findings known to other scientists or to the public.