Scientific Inquiry
What Is Science?
Science is the investigation and exploration of natural events in order to solve problems or answer questions. Scientists may investigate such natural events as how plants perform photosynthesis, how a chemical reaction occurs, or the relationship between plate tectonics and earthquakes. These investigations are based on questions scientists have about the world around them, and they serve as a way to solve scientific problems. Science also refers to the body of information that results from these investigations.
Science covers a vast amount of information, and scientists usually specialize in a narrower field of science. Biology is the study of living things. Some common fields within biology are zoology, botany, and ecology. Physical science is the study of matter and energy, and is often divided into two main branches: chemistry and physics. Chemistry is the study of the properties of matter and how matter changes, while physics is the study of the interactions between matter and energy such as forces and motion. Earth and space science includes such fields as geology, oceanography, and astronomy. It should also be noted that there is much overlap between different fields of science and that scientists specializing in different fields of science often work together. For example, a scientist studying astronomy needs to know a lot about physics to understand and study the movement of planets in the solar system, and a biologist needs to know a lot about chemistry to understand and study how chemical reactions occur within organisms.
When conducting investigations, scientists use a variety of skills, such as observing and inferring. Observations are the results of using one or more of your senses to gather information and taking note of what occurs. Observations obtained during an experiment are usually called data or results. An inference is a logical explanation of an observation that is drawn from prior knowledge or experience. Some other skills used by scientists include describing, identifying, classifying, estimating, analyzing, calculating, and evaluating.
Scientific Inquiry
When scientists "do" science, they engage in scientific inquiry. Scientific inquiry is a process that uses a variety of skills and tools to answer questions or to test ideas about the natural world. The National Science Education Standards (NSES, page 23) defines scientific inquiry as "the diverse ways in which scientists study the natural world and propose explanations based on the evidence derived from their work. Scientific inquiry also refers to the activities through which students develop knowledge and understanding of scientific ideas, as well as an understanding of how scientists study the natural world."
Scientific inquiry often involves a series of steps that are used to solve a problem or answer a question. This series of steps is often called the scientific method (Figure 1). It is important to remember that different scientific questions lend themselves to different types of scientific investigations. There is no one particular pathway that must be followed in every investigation. As you can see in Figure 1, sometimes steps of the scientific method may be repeated, left out, or the entire process may be restarted as new information is discovered. And often scientists will not use the scientific method at all, but instead use other strategies better suited to solving the problem they are investigating.
When using the scientific method, a scientist typically begins with identifying a problem to be solved or by asking questions about something that is observed. After identifying a problem a scientist will often do background research or gather information about the problem. The information gained from research helps the scientist learn important facts related to the problem and can help the scientist form a better hypothesis.
Background research and gathering information are similar, but there is a difference between them. When someone does research, they may look for information in books, magazines, or scientific journals, interview experts, watch videos, or search for information on the internet. Gathering information could refer to the same types of research, but it could also be, for example, what a doctor does when taking care of a sick patient. The doctor may do such things as take the patient's temperature, check the patient's throat and ears, listen to the patient's heart and breathing, and ask questions about how the patient feels.
In the third step of the scientific method, a scientist would form a hypothesis. A hypothesis is a possible explanation for an observation or answer to a scientific question that can be tested by scientific investigation. A hypothesis must be testable using an experiment or some other type of investigation, so that data and observations can be obtained that either support or disprove the hypothesis.
When a scientist forms a hypothesis, it will often be written as a prediction. A prediction is a statement of what will happen as a result of something else. Scientists make predictions based on what they think will happen when they test their hypothesis. One way to do this is to write an if-then statement in the form: If this is done, then this will happen. For example, a hypothesis could be written that states: If the temperature of water in a beaker is increased, then the amount of sodium chloride that can be dissolved in the water will increase.
In the fourth step of the scientific method a scientist would test the hypothesis by performing an experiment or by performing some other type of investigation. When performing an experiment, it is important to use a controlled experiment in which only one variable is changed at a time. Variables are any factors in an experiment that can change.
In a controlled experiment, all of the factors are kept the same except the one factor being tested. The factors in an experiment that do not change are called constants. The one factor that is purposely changed by a scientist in order to test the hypothesis is called the independent variable. The factor that is observed or measured during an experiment is called the dependent variable.
A controlled experiment uses two or more groups for comparison. A group that is used to study how a change in the independent variable changes the dependent variable is called an experimental group. A controlled experiment may also have a control group, which is a group that contains the same factors as the experimental group, but the independent variable is not changed. A controlled experiment must have two or more groups so comparisons can be made, but it does not have to have a control group. A good example of this is the classic science fair experiment in which a student compares the battery life of different brands of batteries (Figure 2). There is no control group, but there may be several experimental groups, and to make the results more reliable, as many different brands of batteries as possible should be tested.
In an experiment, if more than one variable is changed at a time, it is not possible to determine if changes in the dependent variable (the variable being measured) were due to changes in the independent variable (the variable being tested in the experiment), or due to changes in other variables that were not kept constant. This is why it is necessary to control all of the factors other than the independent variable, because data and observations obtained from experiments that are not controlled, and the conclusions based on such data, would be unreliable.
Another way scientists increase the reliability of an experiment is to perform multiple trials. For example, imagine in the battery experiment described above that you only tested each brand of battery one time. How sure would you be of your results? Would you really be confident in concluding which battery has the longest life? Now imagine you performed the experiment several times, maybe testing each battery 10 times. After averaging the results for each brand of battery you would be much more confident in concluding which brand of battery has the longest life. It is extremely important to remember that by performing multiple trials and averaging the results, scientists can have more confidence in their results and the conclusions they draw from those results.
Data collected from experiments can be described as either qualitative or quantitative. Qualitative data are observations that don't involve numbers or measurements. They are descriptions of how an object looks, feels, smells, sounds, or tastes. Quantitative data are observations that are measurements, found using scientific tools or by counting the total number of objects in a group. Qualitative data are subjective, which means that they are based on personal opinion and bias, whereas quantitative data are objective, which means they are not based on personal opinion and bias. For example, when describing the color of a roseate skimmer dragonfly (Orthemis ferruginea) (Figure 3), different people could describe its color as light-purple, violet, lavender, lilac, or pink, just to name a few, but if asked to measure the length of the insect, most everyone would be within one or two millimeters of the actual length.. Both types of observations can be useful, but scientists prefer to use quantitative observations whenever possible, especially in experiments, because they are not based on opinion and bias.
The fifth step of the scientific method is to analyze the results obtained during the experiment. Data can be organized into tables, charts, and graphs, which can then be analyzed for trends and patterns. It is also important to evaluate the quality of the data: Is there data that needs to be thrown out? Do trials need to be repeated? Or if there are serious problems, it may be necessary to troubleshoot the procedure and attempt the experiment again. After the data has been analyzed, a summary of results can be written which summarizes what was discovered in the analysis of the data. The summary is also the place to discuss variables that could not be controlled and other problems encountered during the experiment.
In the sixth step of the scientific method a scientist draws conclusions. These conclusions should be based on the analysis of the data in the previous step. A conclusion can be a simple statement that tells whether the hypothesis is supported or is not supported. It should be noted that the question, hypothesis, and conclusion are all interrelated. For example, a scientific question could be, "What brand of battery has the longest life?" A hypothesis based on this question could be that Energizer batteries will last the longest. If the data showed that Energizer batteries did last the longest, a conclusion could be a simple statement such as, "Energizer batteries have the longest battery life." But if the data showed that Duracell batteries lasted the longest, the conclusion would be a statement that describes how the hypothesis was not supported, for example, "Energizer batteries do not have the longest battery life."
The final step of the scientific method is to communicate the results. When doing this a scientist would describe the entire process used in the investigation from beginning to end, not just the results or data obtained from an experiment . Scientists often publish their findings in scientific journals or by presenting their results to other scientists. Students in science classes typically communicate the results of the experiments and investigations they perform in class by doing such activities as writing lab reports, answering lab analysis questions, or presenting to their teacher and classmates.