Understanding the Scientific Method Part 1
Scientists use the Scientific Method every day to make new discoveries about the nature of our world. The method begins by asking a question about something based on observations. For example, if you add salt to water how does it affect the temperature at which water boils (the boiling point). Water always boils (without salt) at 212 degrees F or 100 degrees C. But what if you add salt? Many people add salt to a pot of boiling water when they are cooking, why?
Next scientists will think of a hypothesis, which is a untested potential answer to their question based on what they already might know or an inference they might have. An inference is an insight made about observationsand experiencesyou have had. For example, you might know that cooks often add salt to boilingwater to delay the boil. Your hypothesis might be that salt increases the temperature at which water boils (raises the boiling point) based on your observations and experiences of cooking. Scientists next research everything that is known on the subject. Other scientists may have some insights or answers to the question as well! Research provides insight into how to go about testing a hypothesis, a critical step in science!
Scientists then need to design an experiment to test their hypothesis. An experiment must keep everything controlled except for the one thing being tested. Things that can vary or change in an experiment are called variables. All the variables in an experiment must be controlled except the one thing you are testing. For example you might boil 10pots of water and add a different amount of salt to each pot. The amount of salt is the thing being tested and is called the manipulated variable. It is being changed or manipulated on purpose. Or you might use the same amount of salt each time but vary the amount of water that you boil. Now the amount of water is changing so it is the manipulated variable. It’s important to control all variables in an experiment except for the manipulated variable! Otherwise you can’t know what is affecting the results in your experiment. Identifying all the variables is crucial in science experiments.
When scientists do experiments they collect data(measurements) from the experiment. For example each time they add salt to boiling water they would write down the temperature that the water boiled at. Sometimes they collect a great amount of data and it needs to be analyzed. To analyze means to make sense of the data. Math is the tool for analyzing data. Computers are often used to mathematically analyze data quickly, but remember that humans write the programs or instructions that computers use. Finally, scientists reach a conclusion about their hypothesis and share what they have learned with other scientists. Their hypothesis was either correct or not, but if their experiment was well designed, then they have a better understanding about their question. The scientific method often generates new questions. For example, if you learn that adding salt to water increases the boiling point, then the next obvious question might be why? Once a scientist develops a new hypothesis to the new question he or she has already begun anew the process of the scientific method! Facts gathered using the scientific method contribute to Scientific Theories and Scientific Laws. A scientific theoryis a well tested explanation about an aspect of Nature that encompass broad scientific knowledge. Scientific theories are reinforced by ongoing experimentation and frame our understanding of reality. A scientific law is a rule of nature that has been verified repeatedly. For example the law of gravity states that all objects of mass in the universe attract each other. There are no exceptions to scientific laws. Science is a dynamic field that remains open to new ideas if they are well vetted by scientific method and meet the consensus of other scientists. For example, although Newton established the basis for our understanding of gravity, Einstein provided new evidence that modified our theory of gravity. We can expect that our theories will continue to evolve, as limits to our knowledge will always be with us. But the big idea here is that scientific method has proven itself to be the best tool Homo sapiens have for understanding the complex physical realities of Nature.