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Science Skills: Let the Student Design the Experiment!


In my many years of teaching, I have discovered that my students do not truly understand how to apply the scientific method.  When they reach my high school biology class, they can recite the steps to the scientific method, but few can actually design a controlled experiment.   Most science teachers (me included!) have our students complete “cookbook” labs in which the student follows a list of steps and hopefully reaches the desired outcome or conclusion.    I am trying to move away from this approach and make my labs more inquiry driven.  This is no easy task!!  Due to overloaded classes, time constraints  and nonexistent budgets, few science teachers can take a class to the lab and turn them lose for independent lab work.

With all of that in mind, I have written this “Student Designed Experiment” that has worked very well for me.  Here are the main points:

  • In this activity, all students will be designing a lab on the same topic and using the same simple materials. This is essential when you first begin to teach your students how to design an experiment.  On the first attempt, you do NOT want your students going in a million different directions.  If all students are working on the same topic, they can help and guide one another, and it allows you, as the instructor, to better assist the struggling students.
  • In the activity that I use, students are asked to design an experiment to determine how various quantities of water will affect the germination of seeds.  It is a very simple topic.  I don't want my students getting bogged down in the subject matter.  I just want them to focus on the steps of the scientific method and how to design an experiment.
  • There are only a very few ways in how to design this experiment.   Perfect! This keeps all of the students moving in the same direction.  This makes your role as facilitator easier, especially if the class size is large.  If this is the first time your students have tried to design their own experiment, the limited possibilities in experimental design will help your students learn the process with less frustration.
  • This requires very simple materials:  Petri dishes or other similar container, radish seeds, graduated cylinder, and water.
  • In this activity, students are asked to identify the independent and the dependent variables.  They must also describe their experimental group and their control group.
  • Students must design a data table and construct a graph of the data they collect.
  • The handouts that I have developed for this activity can be used over and over.  If you have another idea for a ”student designed experiment”, you can have your students use these same handouts.
  • If time allows, you might want to have your students design a second experiment that tests a different variable, such as the effect of temperature on seed germination or the effect of pH on seed germination. 

The process of teaching the "student-designed experiment" is somewhat time consuming, but in my opinion, is well worth the time and effort. This lesson cannot be completed in one class period. I require that students first submit their experimental design to me for approval. I make suggestions, and have the students refine their experiment. Next, students are in the lab to actually carry out their experiment. Students must return to the lab at different time intervals to count their germinated seeds. Students must analyze their data, graph the results, reach a conclusion, and turn in their final packet of work. As you can see, this cannot be done in a 50-minute class period. However, when your students have completed the activity, they should have a firm and concrete grasp on the scientific method and how to design a controlled experiment.

You can find the lab handouts that I use with my students in my TpT store by clicking on the red links.  There are two sets of handouts included.  The first set is used to carry out the seed germination experiment.  The second set can be used all year long as your students continue to design and carry out experiments on topics of their choice.

 Scientific Method Lab: The Student-Designed Experiment

Enjoy!  (...and Good Luck!!)


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