The Scientific Method: Would it Be Less Confusing to Call it Experimental Design?

I have been reading through several online forums lately, and it is that time of year when campuses are gearing up for their annual science fair.  I came across one specific teacher who was asking for advice on how to teach and help his students follow the scientific method. It will be the first time he’ll have his students enter their projects in a science fair, and he wanted his students to be successful! He specifically wanted some help with writing hypotheses for his students’ projects.

At first I thought, why not provide a simple response? I could reply that there is no such thing as the scientific method and that most science fair projects need to be experimental investigations.  I’m sure the guidelines for the science fair are pretty detailed in outlining the development of a hypothesis, a procedure, the collection of data, and a conclusion; however, when reading further about the investigation, I could see how the confusion began: Several students wanted to investigate hatching butterflies in their classroom!

I began to wonder what the variables in that investigation would be and if it was even an experiment at all.  Perhaps, he would be leading his students in more of a descriptive study than an experiment.  This is one of the stumbling blocks most new science teachers encounter when they are being diligent in teaching science and wanting to engage students in authentic scientific investigations.

Scientists don’t usually begin their investigations by stating a hypothesis.  They first need to clarify what it is they are investigating and studying.  Of the several things they need to consider, scientists determine if they are planning to change one part of it or just observe it as it is?  Will they compare things in the natural world or design something to solve a problem?

Although the most well-know type of scientific activity is conducting an experiment to explain the effect of changing one part of the system, there are several other types of investigations that scientists use in their labs.  Some of these include experimental investigations, descriptive investigations, comparative investigations, and researching other scientific discoveries.  Not all of these require a hypothesis. Although all of these are valid investigations, the steps that are followed depend on what is being studied!

In the science classroom, teachers also include several other activities, such as engineering design challenges, project-based learning, and writing research papers to investigate something of interest.  None of these require a hypothesis either, although these are valid investigations as well.

Here’s an easy rule of thumb to consider: when guiding students toward designing a science fair project, ask if they will only be observing something, such as how fast a seed germinate will grow when planted, and recording their observations about it. That would be a descriptive investigation, and no hypothesis is written. If they are comparing two things, such as which paper towel absorbs the most liquid, and recording their observations about how much water each absorbs, then that would be a comparative investigation.  Again, no hypothesis is written. However, if they are going to study something that is a natural system and will change one aspect of the natural system, such as growing six plants of the same type, in the same location, and then adding fertilizer to three of the plants, and recording their observations about each plant, that would require a hypothesis.  Simply stated, a hypothesis is a statement of the test that is being conducted.  It is not a guess or even an educated guess because students will use their prior knowledge. They will state what they know about the effects of fertilizer to guide what they will test and what they will measure.

There is much more to consider when setting up an experiment, such as making it a fair test, which involves keeping everything the same except the one change being made. Although relatively easy to conduct, understanding how these differ is rather sophisticated.  I’d like to invite you to share your ideas for teaching your students the differences in these investigations and perhaps some tips for setting up successful scientific investigations for your school science fair.

Share with us your ideas and experiences as comments to the blog this month!  I hope Talley’s Take becomes a place where you and others can share your thinking about being a STEM teacher and a place where you can comment and ask questions about what others find to be highly effective strategies for teaching in STEM content fields.

This month, Talley’s Take is focusing on science investigations for your students.  Check out the STEM-ify It video. It showcases how using investigations in the science classroom stimulate student thinking, critical observations, and thoughtful responses among students. I look forward to your comments!


Terry Talley, Ed.D.

STEMcoach in Action!



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