Scientific method facts for kids
Scientific method refers to ways to investigate phenomena, get new knowledge, correct errors and mistakes, and test theories.
The Oxford English Dictionary says that scientific method is: "a method or procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses".
A scientist gathers empirical and measurable evidence, and uses sound reasoning. New knowledge often needs adjusting, or fitting into, previous knowledge.
Contents
Stages
Science and things that are not science (such as pseudoscience) are often distinguished by whether they use the scientific method. One of the first people to create an outline of the steps in the scientific method was John Stuart Mill.
There is no one scientific method, but in general it is usually written as a number of steps:
- Come up with a question about the world. All scientific work begins with having a question to ask or a problem to solve. Sometimes just coming up with the right question is the hardest part for a scientist. The question should be answerable by means of an experiment.
- Create a hypothesis – one possible answer to the question. A hypothesis in science is a word meaning "An educated guess about how something works". It should be possible to prove it right or wrong. For example, a statement like "Blue is a better color than green" is not a scientific hypothesis. It cannot be proved right or wrong. "More people like the color blue than green" could be a scientific hypothesis, though, because one could ask many people whether they like blue more than green and come up with an answer one way or the other.
- Design an experiment. If the hypothesis is truly scientific, it should be possible to design an experiment to test it. An experiment should be able to tell the scientist if the hypothesis is wrong; it may not tell him or her if the hypothesis is right. In the example above, an experiment might involve asking many people what their favorite colors are. Making an experiment can be very difficult though. What if the key question to ask people is not what colors they like, but what colors they hate? How many people need to be asked? Are there ways of asking the question that could change the result in ways that were not expected? These are all the types of questions that scientists have to ask, before they make an experiment and do it. Usually scientists want to test only one thing at a time. To do this, they try to make every part of an experiment the same for everything, except for the thing they want to test.
- Experiment and collect the data. Here the scientist tries to run the experiment they have designed before. Sometimes the scientist gets new ideas as the experiment is going on. Sometimes it is difficult to know when an experiment is finally over. Sometimes experimenting will be very difficult. Some scientists spend most of their lives learning how to do good experiments.
- Why-questions. Explanations are answers to why-questions.
- Draw conclusions from the experiment. Sometimes results are not easy to understand. Sometimes the experiments themselves open up new questions. Sometimes results from an experiment can mean many different things. All of these need to be thought about carefully.
- Communicate them to others. A key element of science is sharing the results of experiments, so that other scientists can then use the knowledge themselves and all of science can benefit. Usually scientists do not trust a new claim unless other scientists have looked it over first to make sure it sounds like real science. This is called peer review ("peer" here means "other scientists"). Work that passes peer review is published in a scientific journal.
Although written as a list, this is really a cycle: a scientist may go round it a number of times before being satisfied with the answer.
Not all scientists use the above "scientific method" in their day to day work. Sometimes the actual work of science looks nothing like the above. But on the whole it is thought to be a good method for finding out things about the world, and is the model for thinking about scientific knowledge most used by scientists.
Elements of the scientific method
- Characterizations (observations, definitions, and measurements of the subject of inquiry). This frequently involves finding and evaluating evidence from previous experiments, personal scientific observations or assertions, as well as the work of other scientists. Scientific measurements are usually tabulated, graphed, or mapped, and statistical manipulations, such as correlation and regression, performed on them. The measurements might be made in a controlled setting, such as a laboratory, and often require scientific instruments such as thermometers, spectroscopes, particle accelerators, or voltmeters, and the progress of a scientific field is usually intimately tied to their invention and improvement.
- Hypotheses. At this stage scientists should try to find explanations of the observations they made and measurements they took of the subject. They are free to use whatever resources they have – their own creativity, ideas from other fields, and so on – to imagine possible explanations for a phenomenon under study. The history of science is filled with stories of scientists claiming a "flash of inspiration", or a hunch, which then motivated them to look for evidence to support or refute their idea.
- Predictions. Scientists then try to make predictions about their hypothesis or theory. These predictions are done by deductive reasoning. They might predict the outcome of an experiment in a laboratory setting or the observation of a phenomenon in nature. The prediction can also be statistical and deal only with probabilities. If the predictions are not accessible by observation or experience, the hypothesis is not yet testable and so will remain to that extent unscientific in a strict sense. A new technology or theory might make the necessary experiments feasible. For example, while a hypothesis on the existence of other intelligent species may be convincing with scientifically based speculation, no known experiment can test this hypothesis. Therefore, science itself can have little to say about the possibility. In the future, a new technique may allow for an experimental test and the speculation would then become part of accepted science.
- Experiments. Scientists then need to conduct a series of experiments to see if their hypothesis and predictions were right. Depending on the predictions, the experiments can have different shapes. It could be a classical experiment in a laboratory setting, a double-blind study or an archaeological excavation. Even taking a plane from New York to Paris is an experiment that tests the aerodynamical hypotheses used for constructing the plane.
Failure to develop an interesting hypothesis may lead a scientist to re-define the subject under consideration. Failure of a hypothesis to produce interesting and testable predictions may lead to reconsideration of the hypothesis or of the definition of the subject. Failure of an experiment to produce interesting results may lead a scientist to reconsider the experimental method, the hypothesis, or the definition of the subject.
Other scientists may start their own research and enter the process at any stage. They might adopt the characterization and formulate their own hypothesis, or they might adopt the hypothesis and deduce their own predictions. Often the experiment is not done by the person who made the prediction, and the characterization is based on experiments done by someone else.
Example: dissolving sugar in water
Let's say we are going find out the effect of temperature on the way sugar dissolves in a glass of water. Below is one way to do this, following the scientific method step by step.
Aim
Does sugar dissolve faster in hot water or cold water? Does the temperature affect how fast the sugar dissolves? This is a question we might want to ask.
Planning the experiment
One simple experiment would be to dissolve sugar in water of different temperatures and to keep track of how much time it takes for the sugar to dissolve. This would be a test of the idea that the rate of dissolving varies according to the kinetic energy of the solvent.
We want to make sure to use the exact same amount of water in each trial, and the exact same amount of sugar. We do this to make sure that the temperature alone causes the effect. It might be, for example, that the ratio of sugar to water is also a factor in the rate of dissolving. To be extra careful, we might also run the experiment so that the water temperature does not change during the experiment.
This is called "isolating a variable". This means that, of the factors which might have an effect, only one is being changed in the experiment.
Running the experiment
We will do the experiment in three trials, which are exactly the same, except for the temperature of the water.
- We put exactly 25 grams of sugar into exactly 1 liter of water almost as cold as ice. We do not stir. We notice that it takes 30 minutes before all the sugar is dissolved.
- We put exactly 25 grams of sugar into exactly 1 liter of room temperature water (20 °C). We do not stir. We notice that it takes 15 minutes before all the sugar is dissolved.
- We put exactly 25 grams of sugar into exactly 1 liter of warm water (50 °C). We do not stir. We notice that it takes 4 minutes before all the sugar is dissolved.
Drawing conclusions
One way that makes it easy to see results is to make a table of them, listing all of the things that changed each time we ran the experiment. Ours might look like this:
| Temperature | Dissolving time |
|---|---|
| 1 °C | 30 min |
| 20 °C | 15 min |
| 50 °C | 4 min |
If every other part of the experiment was the same (we did not use more sugar one time than the other, we did not stir one time or the other, etc.), then this would be very good evidence that heat affects how fast sugar is dissolved.
Historical aspects
Elements of scientific method were worked out by some early students of nature. Ibn al-Haytham (Alhazen) (965–1039), Robert Grosseteste (1175–1253) and Roger Bacon (1214–1294), all made some progress in developing scientific method.
However, it was not until the 17th century that the experimental method was agreed to be the main way to find the truth. This was done in western Europe by men like Galileo, Kepler, Hooke, Boyle, Halley and Newton. At the same time, the microscope and the telescope were invented (both in Holland), and the Royal Society was formed. Both instruments and societies helped science greatly.
Related pages
Images for kids
-
Ibn al-Haytham (965–1039). A polymath, considered by some to be the father of modern scientific methodology, due to his emphasis on experimental data and reproducibility of its results.
-
Johannes Kepler (1571–1630). "Kepler shows his keen logical sense in detailing the whole process by which he finally arrived at the true orbit. This is the greatest piece of Retroductive reasoning ever performed." – C. S. Peirce, c. 1896, on Kepler's reasoning through explanatory hypotheses
-
Galileo Galilei (1564–1642). According to Albert Einstein, "All knowledge of reality starts from experience and ends in it. Propositions arrived at by purely logical means are completely empty as regards reality. Because Galileo saw this, and particularly because he drummed it into the scientific world, he is the father of modern physics – indeed, of modern science altogether."
-
-
Model of DNA with David Deutsch, proponent of invariant scientific explanations (2009)
.png){kind=icon}
See also
In Spanish: Método científico para niños
