So you have a beautiful brand new science kit, such as a chemistry set, and you want to set up a truly scientific experiment, something really professional, something tightly organized and keenly observed. Sounds like a great idea so far! So where do you begin?
The first step, perhaps the most important step, is a well-thought-out hypothesis. This article provides instructions for how to make a great hypothesis.
A hypothesis is just a question and what you think the answer is. It’s been called an “educated guess.” To write a good one, keep two principles in mind: your hypothesis should be precise and it should be simple. It’s usually written as an “If…then…” statement.
Contrary to what you may believe, most science kit experiments are carried out with a pretty good idea of what will happen. The goal of the experiment is to confirm that idea. And the name of that idea is the hypothesis.
So, if you look at your chemistry set or science kit sitting there with its brand-new bottles and think to yourself, “I’ll bet if I combine the ammonium nitrate with the water it will get colder, that’s what happens in those cold packs,” well, you’ve got a basic hypothesis right there!
If you further start thinking and wondering, “I wonder what would happen if I added a whole bunch of ammonium nitrate to water. Would it get colder faster? Would it drop to an even lower temperature? How do they measure the right amounts to put in those cold pack things?” then you are really thinking like a scientist!
You can expand your hypothesis to read something like the following, “This experiment will measure temperature effects across time from varying amounts of ammonium nitrate dissolved in water. Hypothesis: If a greater amount of ammonium nitrate is added to water, the temperature of the solution will drop faster, and the greater the amount of ammonium nitrate added to water, the lower the end temperature will be before stabilizing.”
You will notice that the hypothesis is very precise, it states exactly and with no fuzziness just what the experimenter will be measuring and what he expects the results to be. A poor hypothesis would be the following, “Hypothesis: Adding ammonium nitrate will make the water colder.” It is not at all precise. Colder than what? It’s not simply water after you add ammonium nitrate is it? It’s a solution. What do you mean by “colder”? How are you measuring this? The above hypothesis answers all these questions with exactness.
You will also notice that the original hypothesis is very simple. It uses as few words as possible. A poor hypothesis would be the following, “When I add greater amounts of ammonium nitrate from the chemistry set to the water to make a solution like in a cold-pack from the store, then measure the temperature as described, I expect to see the numbers go down quicker than they would with a small amount of ammonium nitrate. I also think there will be a point that the temperature stops dropping and levels off, but I think that point will be lower for larger amounts of ammonium nitrate.” The original hypothesis keeps things very simple.
A good hypothesis guides your experiment. Every observation is taken with an eye to disproving that hypothesis. Yes, you heard right DISproving the hypothesis. A good scientist knows that the best way to prove the hypothesis is right is by trying to prove it is wrong.
A good scientist is very, very careful and critical at each stage of the experiment, recording exactly what happens and noticing every detail that could potentially be impacting the results and disproving the hypothesis. A good scientist carefully repeats trials and reanalyzes data looking vigilantly for flaws. A good scientist uses all of the materials available in the science kit to test the hypothesis. In the end, if the results still match his hypothesis, then and only then can he begin to say it might be true. A good scientist still wants to see that this success is repeatable, so he may run the whole experiment again at another date, or ask a fellow scientist to do so.
If the results do not support the hypothesis, then the scientist has really learned something! Is it time to get a new chemistry set because this one doesn’t give you the results you were looking for? No, that is not the right conclusion. This is where the most interesting part of science comes in, follow-up investigative experiments. The hypothesis is just your best guess, so you don’t really know whether or not it is true. This is where a science kit begins to have all the thrill of a detective novel as you the scientist carefully watch for clues, racks your brain for alternative explanations and likely culprits, or devise plans to follow up a hunch. In which case, you get to write another hypothesis!