Thinking like a Scientist

Independent variable (manipulated variable): factor in an experiment that a scientist changes or controls It does NOT change because of what happened in the experiment! e.g. how much water to give plants (the water itself does not change because of how much was added to the plants) Dependent variable (responding variable): factor in an experiment that a scientist wants to observe, measure or count, it may change in response to the independent variable e.g. how much the plants grew, if at all, because of how much water they were given Constants (controlled) variables: factors in an experiment that a scientist purposely keeps the same Time, temperature, type of plant, type of pots, type soil in each pot, amount of light each plant got, etc.

Analyze Data: See if your data supports your hypothesis

Draw conclusions: A conclusion is a logical idea developed from doing an experiment, it answers the starting question or hypothesis and is based on data and observations

Researchers often work in teams to analyze, review, and check (critique) each other’s work, including conclusions from experiments

Why would they want to do this? Scientists need to check that other people’s work is correct. A review process helps ensure conclusions are valid (correct). To be valid, a conclusion must be based on good, logical interpretations of well planned experiments and reliable data. “You haven’t confirmed the Superstring Theory, this is a whisker from your beard !”

How does a scientific theory develop? As evidence from many investigations or experiments done by many different scientists builds up, a hypothesis that has been found true many, many times may become so well supported that scientists consider it a theory

How does a scientific theory develop? Theory: a well-tested explanation that unifies (ties together) many different observations or experiments

Scientific Theory vs. Common Use Theory Important difference: in everyday life, sometimes theory means a guess (e.g. I think that girl likes me) in science, an idea is tested many, many times and proves itself true over & over before it is called a theory (e.g. I asked her to the prom, she said yes; I asked her to marry me, she said yes; we’ve been married 72 years. There is a lot of evidence that she likes me)

Science is an ongoing process that involves: asking questions collecting observations making inferences testing hypotheses

Scientific understanding is always changing. Good scientists are skeptics who question both existing ideas and new hypotheses.

Science and Human Values Decisions involve many factors besides scientific information, including: the society in which we live economic considerations laws moral principles Citizens decide what to do when they vote.