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Scientific Method
February 7, 2008
A montage of basil plants at various stages of growth

Observation Scientists observe something that they don't understand or that they want to know more about, and ask a question about their observation. NASA scientists have observed that to conduct long-duration missions to other worlds, they need to learn more about how to supply food for astronauts. A question they might ask about this observation is, "How will astronauts obtain fresh fruits and vegetables on missions to the moon and other planets?"
Review background information Scientists look for research that has already been done on their topic to determine if they are duplicating a past experiment, building on a previous experiment, or doing something new. Much of the related research can be found on the Internet. Scientists interested in providing nutritious food to astronauts on trips to the moon would review the research that scientists from NASA and from other nations have already done. They would find that experiments have flown in space in special containers called "plant growth chambers," where conditions such as temperature, light and air can be controlled. The researchers would learn that different types of plants have been tested in space to see if they will grow. They would also learn that no plants have been tested on the moon.
State the problem Once scientists have an idea of the research question they want to study, they state the problem or ask a question. Scientists studying whether fruit and vegetables will grow on other worlds might ask, "Will cinnamon basil seeds flown on space shuttle mission STS-118 grow differently from seeds that have not?"
Form a hypothesis A hypothesis is a statement of what the researcher thinks will happen in the experiment, based on research. The hypothesis must be observable and testable. Addressing the question of whether plants could be grown from space seeds, the scientists might hypothesize, "Seeds that have flown in space will grow the same as seeds that have not."
Design and perform the experiment When designing the experiment, the researcher carefully controls as many variables as possible. (Variables are things that can change, such as temperature and light.) Most experiments have a control group and a treatment group. The two groups are as similar as possible, but the treatment group is the one that experiences the variable that is being studied. An experiment should be designed so that data can be collected to answer the question being asked. For example, an experiment to learn the best temperature for growing plants should include a thermometer in its design. NASA's Engineering Design Challenge: Plant Growth Chamber can be used to test the above hypothesis. In the challenge, student scientists will design, build and test a plant growth chamber. They will plant two sets of seeds, observe and record their growth, and conduct experiments with the plants. One set of seeds is the treatment group. These seeds will have traveled on the space shuttle to and from the International Space Station. The other set of seeds is the control group. These seeds will not have been in space. The only difference between the two groups is whether or not they have been in space.
Collect and analyze data An important part of research is collecting data. After the data are collected, they are analyzed. This step often involves organizing data in charts and graphing the information. In this experiment, students will monitor and compare the growth of plants from space-flown and "non-flown" seeds. This data could be used to evaluate the hypothesis that the seeds will grow similarly. Students can record other data, as well. Students can document their observations of how well seeds germinate, and how well plants grow in the chamber.
Draw conclusions After they analyze the data, scientists see if the results support their hypothesis. Depending on the data about the growth of the plants, students can evaluate the hypothesis to determine if space travel affected the seeds.

After completing the experiment, students should consider repeating the experiment for the most accurate results.

A final step to the scientific process is to present or publish the findings to allow scientific colleagues to critique the studies. Sharing results with the scientific community allows others to review the work and build on the results.

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Page Last Updated: November 3rd, 2013
Page Editor: NASA Administrator