Scientific Method

Core Concepts

The scientific method is a set of steps that scientists may use to create and execute experiments to find answers to important scientific questions. Variations of the scientific method are seen in all fields of science, from forensics to cell biology!

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History of the Scientific Method

The scientific method is one of the backbones of science itself, and its creation is not attributed to a single person or group of people. Rather, the scientific method is the product of centuries of human curiosity and exploration. It is a general idea that has been refined across generations of scientists. For example, Aristotle is widely credited with popularizing the idea that knowledge can be gained based on empirical observations and experimentation. Another example is the Islamic scholar Jabir ibn Hayyan, a cornerstone of early chemistry, who introduced controlled experiments to alchemy, bringing the field into one rooted more closely in logic and justification. However, these examples are just a sliver of the endless scientists who have impacted the modern scientific method. Even today, the scientific method is constantly being evolved and refined.

Steps of the Scientific Method: Preparation for Experimentation

  1. Make an Observation: Observations can be either qualitative or quantitative. A qualitative observation is a form of data that is observed, but not quantified with numbers. For example, that ice is a solid, tomatoes are red, mixing baking soda and vinegar produces a gas, etc. A quantitative observation, on the other hand, is a form of data that is measured and quantified with a numerical value. For example, a person is 160 cm tall, the concentration of salt in the ocean is 35 ppt, etc.
  2. Ask a Question: Based on your observation, propose a scientific question. A good question is specifically defined, testable, and measurable.
  3. Do Background Research: Before starting any experimentation, you want to find out what is currently known by scientists. This way, you can ensure that your decisions are well educated and scientifically backed, rather than an arbitrary shot in the dark.
  4. Form a Hypothesis: A hypothesis is an educated guess to explain your scientific question. It needs to be specific and testable. One special technique that scientists use is the falsification principle, where a null hypothesis (a hypothesis that there is no relationship between variables/groups) is made. By proving the null hypothesis false, one can prove that a relationship exists between different factors.

Steps of the Scientific Method: Conducting and Processing Experiments

  1. Conduct an Experiment: An experiment is a set of designed procedures and observations. In an experiment, only one factor should be changed at a time: the independent variable. The independent variable influences the dependent variable, the variable(s) that is measured. All other variables should be kept constant so it doesn’t impact the outcome of the study, which are known as controlled variables.
  2. Draw a Conclusion: After completing the experiment, scientists will analyze their data and reach a conclusion about their hypothesis. Sometimes, scientists will find that the experimental data contradicts the hypothesis, and then go back, adjust the hypothesis, and conduct additional experiments. Or, they’ll find data that aligns with their hypothesis. Even then, it is still a good idea to repeat experiments, to ensure their reliability.
  3. Communicate Results: Science is a collaborative community, and sharing your results will help future scientists with their experiments! Scientists do this in various forms, from research posters presented at conferences, to research papers published in peer reviewed journals. Peer review is when other scientist provide feedback on one another’s work. Peer review is important to validate the work of other scientists and improve published work. Generally, results are not considered fully realized until they have undergone peer review in a scientific journal.
scientific method flow chart in rainbow colors. the chart goes from "make an observation" to "ask a question" to "background research" to "form a hypothesis" to "conduct experiment" to "draw a conclusion" to "hypothesis is supported". If hypothesis is supported, flows back to conduct experiments. If not, flows back to form a hypothesis. From "hypothesis supported?" flows to "communicate results" then back to "make an observation"
Scientific Method Flowchart

Scientific Method Real World Application

  1. Make an Observation: A scientist notices that different types of milk have varying levels of stability when they are frothed for coffee.
  2. Ask a Question: A scientist proposes the question, what kind of milk produces the most stable foam when frothed?
  3. Do Background Research: When conducting background research, the scientist learns that frothing milk is possible because of the gradual introduction of hot steam into milk, allowing proteins and fats to capture small bubbles.
  4. Form a Hypothesis: Based on the background research, the scientist proposes that milk with a higher concentration of protein should produce a more stable foam.
  5. Conduct an Experiment: To conduct the experiment, the scientist uses milks with various protein concentrations. Protein concentration is the independent variable. Then, the scientist will measure the stability of the frothed milk, the dependent variable, by measuring the time it takes for the bubbles in the frothed milk to collapse.
  6. Draw a Conclusion: After completing the experiment, the scientist finds that the milks with the highest protein did indeed have the most stable foam, which supports the original hypothesis. The scientist will repeat the experiment with multiple trials to ensure that their experiment is accurate.

Conceptual Practice Questions

  1. Categorize the following as a qualitative or a quantitative observation:
    • Ice melts at 100 degrees Celsius.
    • Potassium salts have a lilac color flame
    • Smokers are 20% more likely to get lung cancer
  2. Which of the following is a good scientific question?
    • What state produces the coolest people?
    • Are there extraterrestrial life forms in the universe?
    • Which water purification methods are most effective at removing lead?
  3. When conducting experiments, what kind of variable should stay the same?

Conceptual Practice Answers

  1. quantitative, qualitative, quantitative
  2. Which water purification methods are most effective at removing lead?
  3. controlled variables

Further Reading