How to Use the Scientific Method on the GED Science Test

By Murray Shukyn, Achim K. Krull

It’s a good idea to approach the GED Science test questions using the scientific method. The scientific method is a step-by-step approach to answering science questions and solving problems. It ensures the credibility and reproducibility of experimental evidence.

Now you’d think that for a scientific method to be scientific, all scientists would agree on the steps involved. They sort of do agree, but if you search online for “scientific method,” you’ll find a variety of scientific methods (plural). A good version of the scientific method goes like this, with a couple loops:

  • Observe and wonder. Many of the most important scientific discoveries start with an observation — information obtained primarily through the senses (seeing, hearing, touching, and so on). Alexander Fleming discovered penicillin when he was cleaning up petri dishes in his lab and noticed that around the edges of a patch of mold growing in one of the dishes, infectious staph bacteria had been killed. He wondered, “Why?”

  • Research. Another scientist may have answered the question or solved the problem already. Research provides insight into what’s already been done to answer the question or solve the problem. The research may show that plenty of work has been done and the question or problem remains.

  • Formulate a hypothesis. A hypothesis is a proposed explanation for a condition or occurrence that can be tested and either proved or disproved. A hypothesis can usually be phrased as an if/then question; for example, “If you warm a cup of water, it will dissolve more sugar.”

  • Define variables and controls. Establishing variables and controls is the first step toward designing an experiment:

    • Variables: Conditions that are changed to determine the effects of those changes. In the water/sugar example, heat is the variable being changed.

    • Controls: Conditions that remain unchanged, to prevent them from influencing the results. In the water/sugar example, using water from the same source and making sure the same amount of water is used for each test are controls.

  • Create a procedure. A procedure is a step-by-step process for conducting the experiment or study, including specifics about the data that will be collected and how it will be recorded.

    The procedure is very important because it enables other researchers to evaluate the process used to create and gather data. If the experiment or study is done right, anyone should be able to follow the same steps and get the same results. A poorly designed experiment or study produces unreliable data.

  • List and gather the required materials. Before starting an experiment or study of any sort, the scientist needs to gather all the supplies needed, including, in some cases, participants for the experiment or study.

  • Conduct the experiment or study. It’s show time! Scientists conduct the experiment or study and record the results.

  • Analyze the data. Analysis can be as simple as looking at the data or it may involve plugging it into a spreadsheet, rearranging it, using it to create graphs, and so on.

  • Draw conclusions or not. The results may lead to certain conclusions, may be inconclusive, or may bring up other questions that need to be answered first. In some cases, the conclusions reveal a problem in the design of the experiment or study or the way it was performed.

    The scientific method.

    The scientific method.

Certain steps in the scientific method may vary slightly.

  1. A scientist traveling in Kenya has suffered terribly with nasal allergies for decades. He discovers a group of people who don’t have any allergies. Most of the people are infected with hookworm. He hypothesizes that hookworms may cure his allergies, so he introduces the parasite into his system. Which step(s) in the scientific method did he skip?

    • (A) observation, research, and hypothesis

    • (B) research and variables and controls

    • (C) research, hypothesis, variables and controls, and procedure

    • (D) hypothesis, variables and controls, procedure, and materials

  2. Janice is testing two different fertilizers to see which works better. She uses Fertilizer A on the vegetable garden in her backyard and Fertilizer B on her flower garden in the front of her house. The plants in the vegetable garden grow three times faster and larger than the plants in her flower garden. She concludes that Fertilizer A is the better product. What is wrong with the design of Janice’s experiment?

    • (A) It has no well-defined variables.

    • (B) She did not propose a hypothesis.

    • (C) It has no well-defined controls.

    • (D) Janice forgot to do her research.

  3. Patsy Sherman, a chemist at 3M, was working on developing a rubber substance that would not deteriorate when exposed to jet aircraft fuels. She mistakenly splashed some on her shoe and noticed several weeks later that the areas on her shoe that had the substance on them looked nearly new, while areas without the substance were dirty and stained. She assumed the substance must have been responsible for preserving the shoe. To confirm her suspicions, Patsy needed to conduct

    • (A) research

    • (B) experiments

    • (C) observation

    • (D) analysis

  4. After gathering results and conducting a thorough analysis, a scientist concludes that the results are inconclusive. Which step should he go back to in the process?

    • (A) research

    • (B) hypothesis

    • (C) procedure

    • (D) it depends

Now check your answers:

  1. The scientist made an observation and a hypothesis, so you can eliminate Choices (A), (C), and (D). Choice (B) is the only correct answer.

  2. The problem is that Janice failed to use controls, Choice (C). To perform a controlled experiment, every factor other than the fertilizer needs to be the same in the two groups being tested.

  3. Patsy would need to conduct controlled experiments, Choice (B), to determine whether the substance or something else was responsible for protecting her shoe.

  4. It depends, Choice (D).