The Scientific Method

Which of the following is a good scientific hypothesis?

If a plant is exposed to only blue light, the plant will grow more slowly.

The Scientific Method

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Develop a Hypothesis

Another important step in the scientific method is writing the hypothesis. A hypothesis is an "educated guess" regarding the solution to a problem. The guess is "educated" because you do research before forming a hypothesis; this research is the basis of your position. However, a guess is only a guess until you produce the experimental evidence proving that a given position (solution to the problem) is correct. Unlike some other fields, science demands empirical, or observational, evidence in support of ideas. For this reason, the manner in which you state your hypothesis must fit two criteria: It must be testable. For instance, the hypothesis Space is made of particles that cannot be detected is not a good hypothesis because it cannot be tested. If the premise is that the particles cannot be detected, then there is no way to prove this statement. There are no observations that could be made to support or disprove this statement. It must be falsifiable. Here is an example of a hypothesis that is not falsifiable: Big Foot lives somewhere on Earth today. This statement may or may not be true. There are many tests that could be done that could prove the existence of the legendary Big Foot. However, there is no test that would prove that the animal does not exist. Just because we don't find him doesn't mean he doesn't exist. A hypothesis might then be defined as a proposed explanation for a scientific problem where the explanation can be tested by experimentation. In order for the experimentation to be valid, it must include three main factors: an independent variable—the experimental factor that is changed by the scientist a dependent variable—the factor that changes in response to the change the scientist makes to the independent variable the control—the factor in the experiment that remains constant Make note! Good hypotheses generally take the if-then form because the causal relationship is one that can be tested. A common form is "If the independent variable is changed, then a change will also result in the dependent variable. A good hypothesis must also include these factors, as in the following example: If the voltage is increased to a lightbulb, then the brightness will increase. This statement has an independent variable, a dependent variable, and a control. As the researcher makes changes to the independent variable (in this case, the voltage), the dependent variable (the brightness of the lightbulb) can be experimentally measured. Note that the same lightbulb must be used throughout the experiment. This is the control. If different bulbs were being used, the noted effect could be due to differences in the bulbs, rather than changes in the voltage. The lightbulb hypothesis also fits both criteria discussed above: It is testable—an experiment can be done to support it; and it is falsifiable—that is, when the experimentation is done, there are circumstances that could arise to show that the statement is false. For instance, it is possible that an increase in voltage could bring about no change in brightness or even a decrease in brightness.

The goal of basic research is to invent a new product to sell for profit.

False

The Scientific Method

Louis Pasteur, the famous nineteenth-century biochemist, once said, "Luck favors a prepared mind." In other words, success in the world of research or in the development of new technologies (inventions) doesn't just happen. Scientists have to be observant of the world around them. They have to prepare their minds to see problems and possibilities in everyday life. This disposition is how many inventions, including the Frisbee, come about. Did you know? Originally, the toy was called the "Pluto Platter," but the name was later changed by a marketing company to Frisbee. Frisbee came from Frisbie—note the change in spelling—which was the name of the original tin pie plate. Neither Morrison nor Franscioni simply decided one day that they were going to "invent" a toy. However, they were observant and noticed the popularity of the game played with the flying tin plate. They saw the potential for a marketable product and set out to make a profit. They realized that they could not just sell pie plates, though. They had to do research to determine a suitable material from which a new toy could be made, something that could be mass-produced at a reasonable price. They also did some "flight testing" to improve the line of flight and the distance that the disc could fly. Their research and test trials resulted in a plastic disc with sloping edges that slightly curved under. In the short success story of the Frisbee, you can see all the classic features of good scientific strategy for developing a new invention. Morrison and Franscioni's idea for the Frisbee initially came about because of their careful observation of the world around them. Research allowed them to develop that idea and come up with experiments to test it. Through these tests, they were able to further refine their idea, resulting in the creation of a new, marketable product. Although their process was an informal one, the steps Morrison and Franscioni followed are all part of a formal process called the scientific method. All scientists, researchers, and inventors use some form of the scientific method to make discoveries, solve problems, and create new products. The following chart outlines the steps in the process. Notice that the scientific method is cyclical; that is, it is designed to repeat itself. Almost no researcher or inventor gets it right the very first time. Ideally, with every cycle, the researcher gets closer and closer to the goal. The method described above is likely familiar to you at this stage in your education. While much could be said about each step in the process, two in particular bear a closer look, since you will be using them throughout this course.

Research the Problem

One of the most important steps in the scientific method is researching your idea. A good scientist uses not only his own observations, but the published work of other scientists. Even Thomas Edison, who is credited with inventing the light bulb and the phonograph, relied heavily on the work of others. A tremendous amount of scientific knowledge was being generated by other researchers at the time, and in his laboratory "think tank," one of the most important areas was the library where he did his research. Scientific research generally falls into two categories: applied research and basic research. Applied research results in a new product that can be sold for profit, such as a toy or a technological gadget. The Frisbee is a perfect example of this. Basic research leads to the discovery of fundamental principles that others can build on when pursuing their own research. For example, when Edison invented the light bulb, he based his research on the work of other scientists. He then used his own observations to expand on the basic research they had done.

Objectives

State the steps in the scientific method. Note the two general types of research. Recognize a testable and falsifiable hypothesis.

Let's Review!

The scientific method is a cyclical process that allows scientists to systematically inquire into a problem in order to arrive at a reliable solution. Like Morrison and Franscioni, you do not have to be a scientist or an expert to use the scientific method. Their process was an informal one, but the result was still very successful. The early steps in the process, doing research and developing a hypothesis, allow scientists to ask good questions and pose reasonable, testable answers through experimentation. The laboratory activities throughout this course will require you to form your own hypothesis or test an existing one. Like Edison, you will need to draw on outside research and your own experiences to better understand the question to be answered. At all times you will need to be extremely observant.

In an experiment, the hypothesis is If the wavelength of the light shining on a plant is shortened, the rate of photosynthesis is slowed down. If this experiment is performed, _____.

the result can be determined