Teaching Students the Scientific Method

Scientific method is a tool used by researchers to help them answer questions about the natural world. This special approach helps to ensure that research is objective---free from personal bias.

The steps of scientific method are as follows:1. Have a question.
2. Do background research to find what is currently known about the topic of interest.
3. Develop a hypothesis, an educated guess, predicting the answer to the question.
4. Design an experiment.
5. Conduct the experiment to gather data.
6. Draw a conclusion based on the results. Was the hypothesis supported or refuted?

Student Experiment for Learning Scientific Method

Here is a simple and engaging experiment for teaching junior high through college students about designing and carrying out experiments using scientific method. It is an animal behavior experiment utilizing pillbug (a.k.a. roly-poly or woodlouse). These creatures get their common names due to their behavior of responding to mechanical stimuli by rolling up into a ball.

Pill bugs are crustaceans. Most crustaceans are aquatic (shrimp, lobster, crab), but pillbugs are terrestrial. Although they are terrestrial, much of their behavior relates to their need to avoid desiccation (drying out).

Materials Needed for Pillbug Experiments

The most important thing required for this experiment is several dozen pillbugs. These creatures can be gathered ahead of time by the class instructor. Just look under rocks and leaf piles in the back yard or at a local park.

House the captured pillbugs in a shoebox-size plastic container with holes drilled in the top. Prior to capturing the pillbugs, put a couple inches of moist soil in the bottom of the container, as well as bark or leaves (things for them to hide under). The creatures can be fed with pieces of potato and apple.

It is easy to maintain this original population of pillbugs for years if they are consistently fed and kept moist. The founding captives will breed and generations will follow to replace the bugs that die.

In addition to pillbugs, the other materials required for the experiment include:

* A dozen plastic Petri dishes to use as arenas
* Several small water dropper bottles (filled with water)
* Dark paper cut into circles and half circles that will fit inside a Petri dish.

Running the Pillbug Experiment

Break the class up into groups (of no more than 5 members) and have them design an experiment to investigate the pillbugs' behavior in relation to their need to stay moist.

The students need to choose only one variable to manipulate. A couple of possibilities include...* Cover half of the Petri dish with dark paper (variable dark / light)
* Place two half circles of paper in the Petri dish and moisten one (variable moist / dry)

...however, students can certainly come up with their own ideas to test as well.

The students must carefully plan their experiment, working through all of the steps of the scientific method:1. Ask a question.
2. Develop a hypothesis.
3. State the objectives of the experiment.
4.Design the experiment (listing materials that they will use, outlining the procedure in detail, determining how data will be collected).
5. Analyze the data.
6. Draw a conclusion (Was their hypothesis supported or not?)

It is best for the instructor to approve the students' experiment before they begin, to ensure that the experiment that they have designed is well thought out.

For a printable sheet that prompts students through the steps of this experiment, see The Virtual Cell Biology Classroom main lecture page on Scientific Method. Scroll part way down the page for access to a Word document of the Animal Behavior Pillbug Experiment.