Learning the language:
All sports have their own languages and if a player doesn’t know how to “pick-and-roll”, “give-and-go”, “steal ground”, or “fake bunt” they will not be as successful as those that do. The same is true for science so here are simplified definitions to get you and your “future scientist” started:
• Research: As a verb, research is the process of finding information on a topic. The best strategy is to go to a real library and find published books and peer-reviewed journal articles, but in practice most students will start with Google. Research on the internet can be successful if students rely on websites that end in .edu, .gov, and .mil and verify the informational sources. As a noun, research is the product of all that researching. Students will need to document that they researched their topic by showing their research.
• Hypothesis is a prediction for the answer to the question proposed by the student researcher. The hypothesis is sometimes called an “educated guess”, but this is misleading. The student should not be guessing, but rather making a logical prediction based on information they know or found during their research. Note that a hypothesis is never “right” or “wrong” (after all, who likes to be wrong?) nor is it “proven” or “disproven”. The correct wording is that the hypothesis was supported or unsupported or the hypothesis was accepted or rejected. Sometimes teachers ask that students put their hypotheses into if…then… statements. Although this should not be required, it is an attempt to help you design the experiment.
A general formula for writing a hypothesis would be: If the independent variable is changed in some way, then the dependent variable will change is some way. For example:
If temperature increases, then viscosity will decrease
• Variable (noun) is a part (or factor or item or component) that could have at least two and possibly many different values.
• Quantitative Variable is a variable measurable with numbers (e.g., temperature, speed, weight)
• Qualitative Variable is a variable describable with adjectives (e.g., hotter, faster, bigger) or categories (e.g., male/female, small/medium/large, red/green/blue)
• Independent Variable is a variable manipulated (changed) by the student. It is independent because the student/scientist chooses its values. The independent variable is also called the manipulated variable and can be qualitative (categories) or quantitative (measurement).
• Dependent Variable is a variable measured as an outcome of the experiment. The experiment is checking to see if the value of the dependent variable depended on the value of the independent variable. The dependent variable is also called the response variable.
**The most competitive projects usually have quantitative dependent variables.
• Constant or controlled variable(s) are any variables that are the same for both the control trials and the experimental trials. These variables are not of interest to the researcher so they are not changed, and consequently these variables are constant. Warning: Students often get confused between a “controlled variable” and the “control” (see below).
• Control (noun) is a trial without the independent variable present (or the lowest/highest value of the independent variable depending on the hypothesis). The results of the control trials will be compared to the results from the experimental trials in order to evaluate if there is a difference related to the presence or value of the independent variable.
• Replicates: Repeated trials or measurements to show precision of results (i.e., how repeatable is the outcome?). An absolute minimum of 3 are required in a competitive project.
The following are words that are misused:
• Theory: Many people use “theory” when they mean “idea”. For example, when someone says “I have a theory about that”, they usually mean they have an idea or a thought or a possible explanation. In science a theory is a well tested, widely supported, explanation of a natural phenomenon accepted as true by most scientists in that field. Examples include the Theory of Island Biogeography, The Theory of Evolution by Natural Selection, and Einstein’s Theory of Relativity. Generally, your science project is not creating a new theory so try not to use “theory” in the project unless you are explaining a specific theory behind the phenomenon you are testing.
• Experiment: Along the same lines, many people use “experiment” when they mean “try out”. You may hear someone say “I’m going to experiment with a new recipe tonight”. In contrast, scientists use experiment for a well designed test of a hypothesis.
• Significant: Here is another problematic word. We often use significant to mean “meaningful” or “substantial”, but to a scientist, significant specifically means you conducted a statistical evaluation of the data and found mathematical support for or against your hypothesis. At the elementary (and middle) school levels, this is well beyond their grade level and unless the student can explain how the statistics are justified, you should not use the term significant. Warning: if a judge asks a student if “the results were significant”, the judge is evaluating the student’s knowledge of this term.
• Prove/Proof: It would be exceptionally rare for a student’s science fair project to prove anything and the idea of “proving” something in science is not the same as “prove” in a court of law. Stay away from this word too. It would be better to state “My results provide evidence for…” or “My results demonstrate that…”
• Causation vs. Correlation: With a well designed experiment, it may be tempting to conclude that the change in the independent variable caused the change in the dependent variable. Here again, there are agreed upon rules for claiming causation. For environmental projects with more than one variable measured, be wary of correlation vs. causation.
A creative example of this is the conclusion that eating ice cream causes shark attacks. A survey in most areas would show that as ice cream sales increase, the number of shark attacks increases. The reality is these variables are both related to a third variable (temperature). In the summer, with higher temperatures, both ice cream sales and shark attack cases (because more people go in the water) would be expected to increase independently of each other.
• Accurate vs. Precise: These words are often used as synonyms, but have specific meanings in science. Accuracy is a measure of how close the data is to the real value and precision is a measure of how repeatable the measurement is.