The scientific method is used when creating and executing an experiment. The purpose of the scientific method is to have a systematic way of testing ideas and reporting results in the process of scientific inquiry. A key component of the use of the scientific method is that it ensures that the experiment should be able to be replicated by anyone. If that is not possible, then the results are considered invalid.
The scientific method consists of six steps:
- Define purpose
- Construct hypothesis
- Test the hypothesis and collect data
- Analyze data
- Draw conclusion
- Communicate results
Before you can use the scientific method correctly in your own experiments, you must have a good understanding of independent and dependent variables. To better understand how the scientific method works in action, consider the following examples of simple experiments you can try yourself in everyday life.
Consider how the scientific method applies in this simple experiment with freezing water under two different conditions.
- Define Purpose: I want to know if water freezes faster on its own or with sugar added to it.
- Construct Hypothesis: The null hypothesis is that there will be no difference in how long it takes the water to freeze, whether or not it has sugar added to it. The alternative hypothesis is that there will be a statistically significant difference in freezing time between the two scenarios.
- Test Hypothesis and Collect Data: Fill two identical containers with the same amount of room temperature water. Add a measured amount of sugar to one of the containers. Place the two containers into the freezer. At regular intervals of 15 minutes, open the freezer and observe the status of the water in each container. Continue until both have completely frozen. Write down the time it took for each container of water to reach a fully frozen level.
- Analyze Data: Look at the time it took for each container of water to freeze. Did the water with sugar added take a significantly longer or shorter amount of time to freeze?
- Draw Conclusion: Based on the results of your experiment, come to a conclusion as to whether water with sugar freezes faster, slower, or at the same rate as water without sugar added.
- Communicate Results: Report your findings in the form of a written report as an oral presentation.
In the case of this experiment, you may choose to vary the amount of sugar added (during step 3 of the scientific method above) to see if it alters the results as well. This could be a more robust experiment as you would then have additional data to report.
Here is another example where the scientific method can be used to study the natural world.
- Define Purpose: I want to know if a bean plant will grow more quickly outside or inside. For the purposes of this experiment, you might decide on a time frame of three weeks.
- Construct Hypothesis: The null hypothesis is that there is no difference between growing a bean plant indoors or outdoors. The alternative hypothesis is that there is a statistically significant difference between the two growing situations for bean plants.
- Test Hypothesis and Collect Data: Plant four bean plants in identical pots using the same type of soil. Place two of these in an outdoor location, and place the other two in an indoor location. Try to choose locations where the plants will get a similar amount of sunlight. Care for the plants in an identical way, like giving the same amount of water. Then, each day for the three-week experimental period, observe and measure plant growth. Carefully record the size of each plant in a notebook.
- Analyze Data: Review the data and determine how the plants in both environments progressed over the course of the three weeks. You may choose to find an average between the two indoor plants to determine the "typical" indoor plant growth, doing the same for the two outdoor plants to calculate the "typical" outdoor plant growth.
- Draw Conclusion: Based on the data you collected, determine if there is a conclusive answer to the question as to whether a bean plant placed inside or outside will grow more quickly.
- Communicate Results: Prepare a way to present the results of the experiment, like in the form of a written report, a slideshow presentation, or as a display at a science fair.
Applications of the scientific method include simple observation too.
- Define Purpose: I want to know if solo drivers are illegally using the carpool lane on the freeway in my city, and if so, how widespread the problem is.
- Construct Hypothesis: The null hypothesis might be that there are zero people driving alone who are using the carpool lane on the freeway. The alternative hypothesis could be that there are a significant number of solo drivers using the carpool lane.
- Test Hypothesis and Collect Data: To test this hypothesis, you might find a pedestrian-friendly overpass from which you can observe the carpool lane on the freeway. For a 60-minute period during rush hour, you tally up the number of vehicles in the carpool lane who have the minimum number of passengers to qualify for the lane, as well as a separate tally for the number of vehicles with solo drivers. (For the purposes of this experiment, we might ignore location-specific exemptions, like how some states allow electric vehicles to drive in the carpool lane regardless of the number of passengers.)
- Analyze Data: Review your data. You might choose to calculate the percentage of vehicles that contained solo drivers.
- Draw Conclusion: Based on the data you collected, decide whether a significant number of solo drivers were using the carpool lane during your observation period.
- Communicate Results: Present your findings in a written or oral presentation.
While a single sampling over a single rush hour in one location may not be representative of a city as a whole, these sorts of observations can be a great starting point for further study and analysis.
The process of executing an experiment using the scientific method ensures that your work is well thought out and organized, and that all data is recorded and can be shared easily. This, along with the possible replication of the experiment's circumstances, reduces any bias on the part of the scientist performing the experiment. Furthermore, the communication of the results allows for peers to review the work to ensure the results are precise, accurate, and correctly interpreted. And all of these components add up to a STEM (or is it STEAM?) education.
When you are ready to present the findings of your own experiments, be sure to follow the correct report writing format. Be mindful of the various elements, as well as your choice of font and use of headings. Keep your science learning going strong by discovering some inventions from the Scientific Revolution.