Experiments

In our last meeting, we discussed the scientific method. I covered a vital part of the scientific method, design and run an experiment, but I’d like to expand a little on that today.

In an experiment, I said we’re always going to have two groups that we test. The first group, the control group, tells us what would happen without our interaction. The second group, the variable group, tells us what happens when we perform our experiment. If our experiment was to test the amount of growth of plants by adding fertilizer, our setup would look something like this:

You can see that only 1 thing separates our control group from our variable group. Our variable, then, is the fertilizer. The variable you choose to change is called the independent variable. The variable that changes based on what you do in the experiment is called the dependent variable.

Note: When designing an experiment be careful to not have more than one independent variable. In the event of more than one, you cannot be sure as to which variable actually resulted in the change you’re measuring. For example, in our experiment if we changed both the amount of water we gave the plants and whether or not we used fertilizer, we couldn’t be sure as to whether a change in plant growth was because we used fertilizer or because some plants didn’t get the same amount of water as the others.

In our example experiment, our independent variable is the fertilizer (specifically, the amount we use). A way to remember this is that it’s the independent variable because it is independent of what’s going on in the experiment. Only the experimenter decides how much fertilizer to use. Our dependent variable is the plants’ growth (the amount of growth measured). A way to remember this is that it’s the dependent variable because it is dependent on the other variable. The amount of plant growth is only affected by how much fertilizer we used.

In an effort to not overload you today, I’ll call it quits. Next time, we’ll have a talk about some famous experiments and how they were improved upon by other scientists. In the meantime, feel free to leave me messages, comments, or questions. You can do that here, on my about page, or on my new Twitter account: @amoebamike

What Is Science?

Last time we met, we said that biology is the study of life. Biology is also known as the science of life, or life science. Today we’ll discuss what science is. You probably have an idea of what science is. Ultimately, at least philosophically, we can say that science is the pursuit of truth. However, we’d like to believe that all subjects strive to find the truth. But science is different than every other type of study out there. You can study languages like English; you can study math; you can study history; you can study religion. The one thing that separates science from those other fields is the scientific process, frequently called the scientific method. Most sources vary somewhat in their specific steps (and even the number of steps) that compose the scientific method, however the process as a whole is the same. The basic steps of the scientific method are as follows:

Ask a question. The most powerful thing the human possess is its inquisitive nature. As long as we are curious, we will continue to grow. So when you look at something and think, “Gee, I wonder why that is?” you’re starting the scientific process. As an example, you might wonder, “Why do bees like flowers?”

Form a hypothesis. A hypothesis is your attempt to answer that question, based on information you already have or can research. So, you might know based on what you have read that bees don’t eat other bugs. Your hypothesis may be, “Bees like flowers because they use flowers for food.”

Design and run an experiment. Now you have to figure out how you can prove that bees use flowers for food. For this, you would need two groups of bees. One would be bees you don’t give access to flowers. If you’re hypothesis is right, then the bees that you keep away from the flowers will starve and die. This first group is called the variable group. The second group of bees, you would do nothing to. This is your control group. The purpose of the control group is to show you what would happen to these bees in nature, if they weren’t in your lab. A great example would be if all your variable bees died and your control bees didn’t. This would mean, whatever was different between the two groups possibly caused the variable bees to die. But if you didn’t have a control group and all your variable bees died, maybe you just got a batch of sick bees and their deaths had nothing to do with your experiment!

Observe and record. During your experiment, a scientist makes many observations. An observation is any gathering of information. You’ll use your senses, or use a specifically designed piece of equipment, to make observations. The information gathered is referred to as data (singular: datum). While observing, you’ll record the data to look over and make any number of decisions with later. In groundbreaking work, the records will also serve to allow other scientists to read what you observed. In the bee experiment, an example of an observation would be “93 out of 100 bees died from the variable group (those withheld from the flowers), and 4 out of 100 bees died from the control group (those that had access to flowers).”

Draw a conclusion. After properly recording your observations, you’ll get to decide what it all means. Analyze your results and come to a final decision on your hypothesis. The decision could just be that the experiment was potentially flawed and should be run again differently (and you would support this conclusion with facts). In our bee experiment the conclusion could be, “Our analysis shows there is a strong correlation (a strong link) between flowers and bees, so it is likely that bees use flowers for food.” Now, we might observe in our experiment that the bees didn’t appear to eat the flowers, so we might suggest a follow up experiment to determine how bees use flowers as food if they don’t actually eat the flowers.

In our next meeting, I’ll give you a little more on experiments. See you then!