Scientific Inquiry /

Recap We make an observation, ask a question, and then make a hypothesis. A hypothesis must be __________. So, how do we do that?

Scientific Inquiry Experiments (aka controlled experiments) the research is conducted in a controlled setting to prevent more than one variable from affecting the outcome. Investigations used when controlled experiments are not possible

Scientific Inquiry As the research is conducted, data are gathered. The data are then analyzed to reach a conclusion Either the data support the hypothesis or the data refute the hypothesis. But, the data never prove the hypothesis.

Scientific Inquiry If the data support the hypothesis, we keep the hypothesis for more testing. After all, it wasn’t proven, just supported. If the data refute the hypothesis, we reject the hypothesis or modify it to fit the data. Then we test some more.

Scientific Progress Scientific knowledge is gained through: -- Following systematic steps Collecting facts (observing) Collecting facts (observing) Developing a hypothesis Developing a hypothesis Researching (experiments / investigations) Researching (experiments / investigations) Reexamining the hypothesis to support, modify, or reject Reexamining the hypothesis to support, modify, or reject -- Theories that withstand examination -- Totally unexpected occurrences

The outline So, scientists generally: Make observations Ask a question Form a hypothesis Test the hypothesis Analyze the results Draw conclusions Communicate results (It’s not done until it’s communicated.)

make observations ask a question form a hypothesis test the hypothesis analyze the results draw conclusions Do they support the hypothesis? no yes communicate results Note: You can always move backward, too.

“Inventing hypotheses or theories to imagine how the world works and then figuring out how they can be put to the test of reality is as creative as writing poetry, composing music, or designing skyscrapers.” F. James Rutherford & Andrew Ahlgren. (1990). Science for all Americans. New York: Oxford University Press.

Check-up Why can’t scientists always progress in an exact sequence of steps through their research process? Why is it sometimes necessary to go backward in the research process?

Scientific Research Scientists measure their variables. Experiments have two types of variables: independent variable purposely changed to look for a resulting change in the dependent dependent variable measured to detect change as a result of independent

Scientific Research I wonder how I can get better grades in science? I think if I take notes in science, I’ll do better on tests. I’ll take notes during the next unit (independent variable). I’ll see if taking notes affects my grade on the unit test (dependent variable).

Scientific Research Measurements need to be as accurate and precise as possible. Measurement tools need to be reliable and valid.

Scientific Research Experiments have two types of variables, and all other factors are kept constant, as much as possible. The constants are the control variables. Experiments have a control. The control acts as a standard for comparison.

Scientific Research In my test of note-taking’s affect on grades, I need to control as many other factors as possible (e.g., keep subject the same from one test to another, keep difficulty the same, do all other studying just as before, etc).

Scientific Research I need to make sure my measurements are accurate and precise. Does the test accurately measure how much I learned? Does the test measure precisely enough to detect differences? For example, a % grade is more precise than a letter grade.

Scientific Research I need to make sure my measurements are reliable and valid. A reliable test will give the same results every time it is used for the same purpose. A broken clock is reliable. A valid test correctly measures what it was designed to measure. An properly working atomic clock is valid.

Scientific Research Does my science test give reliable results? If I take it in the morning, will the results be the same if I take it in the afternoon? Does my science test give valid results? Does the grade I receive on the test truly report my learning of the content of the unit? A valid measure must be reliable, but a measure can be reliable without being valid.

Check-up What is the difference between reliability and validity? What is the difference between accuracy and precision? Why are reliability, validity, accuracy and precision important in science?

Scientific Research Ideally, we’d have a control group. One group of students, randomly selected, would take notes during class. Another group, randomly selected, would not take notes. The second group is the control group. Then, we’d compare test scores at the end of the unit. Did the test group (took notes) do better than the control group?

Scientific Research If the test group averages higher test grades than the control group, our hypothesis has been supported, but not proven. If the test group does not earn higher grades, than the hypothesis has not been supported.

Check-up 1) What are the major branches of science? 2) How do these branches work interdependently to help us understand the world? 3) Explain why science is considered a process. 4) What do these terms mean? hypothesis, experiment, investigation, theory, law, control, variable

Check-up Design an experiment to test the hypothesis: “Pine floats better than oak.” What are your variables? What is your control? What variables will need to be controlled? What will you measure? What tools will you need to use? Make sure to discuss issues of accuracy, precision, reliability and validity.

Homework Plan an experiment to test this hypothesis: 32 psi is the optimal tire pressure for a 2007 Ford Focus 4-door’s gas mileage.