Stability and Change
They say that in life, change is the only constant. Go ahead, jot it down on your list of potential senior yearbook quotes. We'll wait.
Okay, so let's talk about change. Change is happening all the time, all around us. And when it comes to the scientific method, change is what we're looking for. For example, let's say we want to know if a certain fertilizer works. We're going to add it to our soil, in a controlled way of course, and see if it changes the way the plant grows. Obviously we're hoping for a positive change (who doesn't love tomatoes the size of cantaloupes?), but a negative one can be just as telling.
Then there's change's polar opposite, stability. Stability may not be as exciting as change, but it can still help us out with an experiment. For example, when we control our variables, some of them remain stable. With our fertilizer example, we will keep the amount of fertilizer each plant receives stable. The amount of fertilizer given will be our independent variable. Then we'll observe to see if differences in our independent variable affect our dependent variable, plant growth. We'll need to keep outside variables, like type of soil, temperature, and how much water and sunlight is given, stable as well. This allows us to be sure those stable variables didn't cause any hijinks with our experiment that would affect how our plants grow.
Stability can also tell us that whatever we were testing didn't produce any changes. Maybe that fertilizer we were working on produced tomatoes the exact same size as the tomatoes without fertilizer. Not the desired results, but at least now we know we need to redesign our fertilizer.
Change and stability are two big ideas that scientists are constantly looking for, trying to achieve, or using as evidence to explain something, so we're going to see them everywhere. We weren't kidding when we said change is so constant you can never step in the same river twice (make sure you quote us on that in the yearbook, it's S-H-M-O-O-P). Actually, we're pretty sure it was some Greek philosopher who said it, so you might want to change that.