In one of my night classes this week, my lesson plan focused on research methods. As any good scientist knows, before you can really get into the heart and soul of research methods, you have to first make sure that students know about the scientific method. In particular I wanted to draw out the distinction between a theory, a hypothesis, and an operational definition. We started by getting examples of developmental phenomena that students noticed. A student volunteered 'babies suck on their toes' as our starting point. This is something we've observed and something that we might be interested in explaining.
Phenomenon: Babies put their toes in their mouths.
Step two was to come up with a theory that could explain WHY babies put their toes in their mouths. Some of the suggestions were that toes taste good or that babies are curious. I settled on 'toes taste good' as the example theory we'd use. (Note: it would have been better to choose 'babies are curious' for many reasons...)
Theory: Babies put their toes in their mouths because their toes taste good.
Our next step was to come up with a testable hypothesis based on our theory. While theories can be general, hypotheses have to outline a specific, testable relationship between at least two variables. Someone in class noted that after infancy, people pretty much stop putting their toes in their mouths.
Hypothesis: Babies put their toes in their mouths because baby toes are delicious. They stop putting their toes in their mouths because toddler toes don't taste as good.
All things considered, it is actually a decent hypothesis because we now have a specific prediction that we can test. We can design a study to see if baby toes might be more delicious than toddler toes. This hypothesis clearly outlines our independent (IV) and dependent variables (DV): we think that the deliciousness of toes (IV) might be related to how often young kids put their toes in their mouths (DV).
The next step was to operationalize our variables. We had to come up with a specific way to measure both the deliciousness of toes and how often young kids were putting their toes in their mouths.
Operationalizing our IV (deliciousness of toes): People could lick different baby and toddler toes and rate how good they tasted. Our raters would not know how old the toes were that they were tasting. (Reminder: we expect that young toes will taste better than older toes.)
Operationalizing our DV (how often young kids put their toes in their mouths): Someone could watch babies and toddlers for a specified period of time and count how many times they put their toes in their mouths. (We could have also measured the duration of how long toes were left in mouths.)
This is how we came to discuss the deliciousness of baby toes in class. We started by picking a phenomenon. Then we tried to explain why we might observe it. Before we could discuss ways to collect data to test our theory, we had to draft a testable hypothesis about how two specific variables might be related to each other. And finally we had to come up with a really clear method for measuring our variables of interest. Our operational definitions had to be clear enough that anyone else who wanted to conduct a replication of our study would be able to do so. Not that we'd recommend that anyone conduct a blind taste test of baby toes.
Sometimes you commit to a path and things just get weird.