Science comes from the Latin root scio, meaning knowledge. Essentially, the study of science is a method of reasoning to learn more about the world around us rather than a collection of discrete facts or even principles, theories and laws.
Experimentation is how science gets done, but many “experiments” I see online and even in some textbooks are really just demonstrations. Demonstration activities can be important for illustrating scientific concepts and principles, but they are not how scientists learn about their world. Since the scientific method is at the heart of how scientists conduct research, I think it is important that students learn to set up their own experiments and report on the results using the scientific method.
Here, we are going to take a look at how Louis Pasteur’s commitment to the scientific method solved many of the pressing problems of his day. (And he was considered an “average” student in school!) Then we will take a closer look at what the scientific method is and set up a basic experiment.
Louis Pasteur was described as an “average” student, but he went on to do amazing work as a scientist. His commitment to rigorous experimentation to test his theories led him to develop the process of pasteurization, helped him save the silkworm industry, and gave us vaccines against such deadly diseases as cholera, tuberculosis, anthrax and even rabies. His use of the scientific method coupled with his scientific successes also led to the formalization and widespread usage of the scientific method itself.
The development of pasteurization
Seeking to help solve problems with the manufacture of alcoholic drinks, Pasteur soon was able to prove that bacteria was responsible for souring beer, wine, and even milk. He did not invent the germ theory, but through experimentation, he was able to further develop it. He was able to demonstrate that heating a liquid killed bacteria and when it was cooled, it would need to be re-infected for bacteria to begin to grow again.
To demonstrate that this bacteria traveled to the medium on particles rather than as part of the air itself, he set up three groups of flasks with an s-curve in the neck. They were heated to the same temperature and allowed to cool. He left one standing as it was, broke the neck on one and laid the third on its side so that the medium would fill the s-curve. Bacteria began growing in the second two, but not in the first. Even though the air was able to pass through the opening in the s-curve, other particles would get dropped in the bend, preventing bacteria from making it to the medium. The first test was done on April 20, 1862
This experimentation led to the widespread acceptance of the germ theory and also led to industries adopting pasteurization as a method of preserving food around the world.
Saving the silk worm industry
In 1865, Pasteur reluctantly responded to the invitation of an old friend to come to the south of France and research a disease that was devastating the local silkworm industry. He and his students studied the problem for some time and Pasteur finally thought he figured it out. Adult moths with globules passed the disease on to the eggs. Breeders would simply have to sort the females and destroy the eggs of any that had these globules. But he had to wait for the eggs to hatch in order to prove his hypothesis.
The results were devastating. Hatchlings he thought should have had the disease turned out healthy. Others that shouldn’t have it were dying. What was going on? Somewhere, he had made a terrible mistake and he was being attacked from all sides. He and his students persisted, however, and through their careful and consistent experimentation were eventually able to demonstrate that there were actually two diseases attacking the silk worms, not one. He was also able to demonstrate the primary disease he was researching was being passed from worm to worm via droppings on the leaves and the second was passed through the intestines. This information led to better practices that allowed the silkworm industry in southern France to recover and prosper.
Development of vital vaccines
Pasteur’s interest in vaccination was the result of an accident. After mistakenly exposing a flock of chickens to a weakened strain of chicken cholera in 1879, he was able to demonstrate that they became immune to the disease. This led to further research and the development of vaccines to fight anthrax, cholera, tuberculosis and smallpox.
These successes eventually led him to tackle the problem of rabies. Rabies was prevalent in Europe in his day. The only efforts at control involved attempts to control the populations of stray dogs and other animals around the city, but it was not enough. There was no cure and it led to a slow, painful death.
In 1885, a rabid dog attacked a group of children. Joseph Meister, a nine-year-old shepherd boy, stepped in front of the group of children and fought the dog to protect the others. His town considered him a hero and was devastated that this young man of courage faced certain death in response to his selfless actions. They had heard about Louis Pasteur’s work and asked if he might look at the boy. Pasteur administered the first round of his vaccination on July 6, 1885. The boy did not contract rabies and Pasteur achieved near instant international fame. People from all over the world came to see him in France to receive vaccinations for rabies, including an entire group from Russia. Because of the length of travel, some were already exhibiting symptoms by the time they arrived. He treated them with a modified protocol and all but three survived.
People from around the world raised money to fund the Pasteur Institute in Paris in his honor.
Pasteur and the scientific method
Louis Pasteur was not the first to use the scientific method. Inductive reasoning was first promoted as a part of science by Roger Bacon (12-14 – 1284). Its roots can be traced back even further. His systematic use of the scientific method, however, coupled with his incredible discoveries in so many areas, helped to formalize the method and popularize its use among scientists. The scientific method forms the basis of how science “gets done” now. This is especially true in fields like biology and chemistry where the processes being studied can be observed, measured and tested. (It isn’t quite as easy to test theories on how star formation!).
Learning the Scientific Method
Science comes from the Latin root scio, meaning knowledge. Essentially, the study of science is a method of reasoning to learn more about the world around us rather than a collection of discrete facts or even principles, theories and laws. Experimentation is at the core of science, but not science education. Have you noticed how many science “experiments” online and even in textbooks are really just demonstrations and do not employ the scientific method at all?
Demonstration vs. Experiment
A demonstration is an activity that demonstrates a scientific concept or principle. Placing a bean on a moist paper towel in a baggie to show how the seed grows into a bean plant, for example, is a demonstration.
Demonstrations are useful for teaching scientific principles. They illustrate concepts and are very hands-on, drawing children in and keeping their interest. Dropping a Mentos into a bottle of Coke can be a very dramatic introduction to chemistry, making the lesson more memorable. Demonstrations are an important part of teaching science, but they should not constitute the whole of the science curriculum.
An experiment requires a control group and several experimental groups to test variables. You can turn the above demonstration into an experiment by preparing several beans and placing some in a dark closet, some in normal sunlight and some under grow lights for 24 hours per day.
Science happens through experimentation. That’s why I believe it is important to teach even young children the scientific method and help them begin to develop their own experiments and test their ideas systematically the same way scientists around the world do every day. It takes more time and a greater commitment than a simple demonstration, but it goes beyond simply illustrating a concept and teaches children how to reason scientifically. That’s why my goal is to have the children set up one experiment per semester, complete with a lab report.
What is the scientific method?
The scientific method is simply a process of experimentation that allows a scientist to test a hypothesis and publish the results in a format that allows other scientists to repeat the experiments. Repeated experiments yield more reliable results. Not every scientist goes through the steps in the exact same way, but the same general principles guide all good experiments.
When a scientist publishes the results of an experiment, he or she includes enough information about how the experiment was designed so that other scientists can replicate it. Different scientists will also approach the same experiments different ways to try to make sure that what they think is happening really is what is happening.
You can help your child design an experiment to test anything (observable) that they would like and that you have the resources to complete. When first starting out, however, it is very helpful to have an experiment to refer to. This helps teach the structure. Once they have been through the process a few times, they should be ready to begin designing their own experiments. My children had a great time setting up experiments related to those “demonstrations” you find on YouTube. I put demonstrations in quotes because not one of them worked. What they learned is that a little editing can make almost anything seem believable and that you really need to test what you see, even if you think you saw it with your own two eyes.
In this experiment, we are going to go off of Louis Pasteur’s work with pasteurization. We already know what causes food to spoil, so we are going to test the temperature ranges for yeast. You will take three batches of yeast and keep them at different temperatures for ten minutes. You will use the data to determine how well yeast grows at different temperatures. Decide what temperatures you are going to test and prepare how you are going to keep the yeast at that temperature before you begin the experiment.
Before starting, make sure to give your child an opportunity to form a hypothesis about what will happen. Write it down and then begin!
3 (or more) glass bottles (pop bottles work really well if you can find them)
a balloon for each bottle
a thermometer for each bottle
Activate three batches of yeast.
To activate yeast:
Start with 1/2 cup of warm water (100 degrees Fahrenheit). Add 1 teaspoon sugar and 1 packet of yeast (or 2 1/4 teaspoons if you are using a jar). The exact measurements are not so important so long as you make them all exactly the same.
Carefully pour one batch into each bottle.
Attach the balloon to the mouth of the bottle.
Place your bottles in three different places to test the effects of temperature on the yeast. One should be left on the counter and kept at around 100 degrees as the control. When we did this experiment, I didn’t have enough thermometers to test small temperature differences. We left one on the counter, one in the refrigerator and one on in a pot of boiling water.
Wait ten minutes. As the yeast activates and begins eating the sugar, it begins producing carbon dioxide. This produces the bubbles you may have noticed while you were activating your yeast. It also makes the little holes you see in bread. In this experiment, we are testing how active the yeast is by measuring how much carbon dioxide it releases. The more it releases, the more the balloon will fill.
Make notes on what is happening with each balloon every couple of minutes.
At the end of ten minutes, bring all three bottles to the same temperature. It will be quickest to put them all in a cooler of ice to cool them rapidly. Otherwise, you may not be measuring what you think you are measuring. If you decided to put one on the stove, for example, you probably watched the balloon blow itself up rather quickly. This was the effect of hot air expanding, however, not of the yeast. You won’t be able to tell the difference between air temperature variables and yeast activity until all of the groups are at the same temperature. Remember this while you are interpreting the results!
Analyze the data
What happened? Did the experiment prove or disprove your child’s hypothesis? Remember that this isn’t about your child being “right” or “wrong”. It’s about asking a question, formulating a hypothesis, designing an experiment and testing the idea. I try to maintain a fairly neutral tone of voice when we are discussing the results. I don’t say, “Yay! You were right!” or “Hmmm, it looks like you were wrong”. Instead, I say things like, “It looks like the experiment proved your hypothesis. What else could be tested?” Or, “It looks like the experiment disproved that hypothesis. Do you think we need to change the hypothesis or the experiment?”
You can grab this experiment and much more in the Science Celebration Yearbook 2017