Experimental Design & Scientific Method

Section 1 What is Science? You should know this by now!!!

What is Science? A. Science—a way or a process used to investigate what is happening around you 1. Scientists observe, investigate, and experiment to find answers. 2. Scientists also use prior experience to predict what will occur in investigations. 3. Technology is the application of science to make products or tools that people can use.

What is Science? B. Communication in science 1. Thousands of scientific journals and magazines report the results and conclusions of experiments every year. 2. You can also keep scientific data and results in a Science Journal.

Section 2 Doing Science I promise, it won’t hurt a bit!

Doing Science Scientific methods—ways, or steps to follow, to solve problems B. Descriptive research—answering a scientific question by making observations about the question 1. State the research objective. 2. Describe the research design, or how you will carry out your investigation. 3. Eliminate bias, or expected results.

Doing Science 4. Select the best materials for the investigation. a. A model represents things that happen too slowly, too quickly, or are too big, small, dangerous or expensive to observe directly. b. Scientists around the world use a system of measurements called the International System of Units (Metric System) to make observations.

Doing Science 5. Design data tables, or ways to accurately record results and observations. 6. Analyze your data and figure out what your results mean. 7. Draw conclusions. Don’t fall asleep on me yet!!!

Doing Science C. Experimental research design- answering a scientific question by observation of a controlled situation 1. Form a hypothesis, which is a prediction that can be tested. 2. Plan the experiment a. Independent Variable- the factor that is changed. (You can only test one at a time!) b. Dependent Variable- factor that is being measured. c. Constants- variables that stay the same.

Doing Science 3. Use a control- a sample that is treated like the other experimental groups except that the independent variable is not applied to it. 4. Conduct several trials of the experiments. 5. Analyze your results and draw conclusions.

Writing a Hypothesis A hypothesis must contain the words IF and THEN. If I study for a test, then I will get an A. If I eat a lot of sugar, then I will get hyper. If I mix chemical A and chemical B, then they will create a new chemical.

Sample Size The more subjects you test, the more accurate your results. For 8th grade experiments, using 10 or more test subjects could be enough. Scientists must use many more test subjects in order to test their hypothesis.

A hypothesis is….. IMPORTANT Even if it is not SUPPORTED .

Science and Technology Section 3 Science and Technology Which is better…..

Science and Technology A. Scientific discoveries lead to new products that influence your lifestyle. 1. Entertainment- _____________ 2. Convenience- ______________ 3. Health- _____________________ B. Science provides information that people use to make decisions. C. However, science cannot decide whether the new information is good or harmful, moral or immoral.

Now you’re done taking notes… BUT……

Let’s try a problem… Bart thinks that drinking a 32 ounce Mountain Dew before you go skateboarding will help you do a higher ollie in the air. He divides 10 of his friends into 2 groups. To group A, he gives each person a 32 ounce Mountain Dew. To group B he gives nothing. Group A’s average ollie height was 2 feet, and group B’s average ollie height was 1 foot.

What is the problem being solved? Does mountain Dew make you do higher ollies on a skateboard?

What is the control group? Group B

What is the independent variable? Mountain Dew

What is the dependent variable? Ollie height

Is the sample size big enough? For a small experiment, yes. For accuracy, however, more participants would be better.

What is the hypothesis? If you drink Mountain Dew, then you will do higher ollies.

What is his experimental procedure? He divides 10 friends into 2 groups. Group A get Mountain Dew and Group B does not.

What should Bart’s conclusion be? Mountain Dew does cause you to do higher ollies.

Let’s try one more… And you in the front row……quit eating glue!

Last problem…. Homer thinks that adding hot sauce to gasoline will make a car go faster. One day, he adds hot sauce to Marge’s gasoline tank but no hot sauce to his own tank. They both drive to the same grocery store. It takes Homer 25 minutes to get there and Marge 20 minutes to get there.

What is the problem being solved? Does hot sauce make a car go faster?

What is the control group? Homer’s car

What is the independent variable? Hot Sauce

What is the dependent variable? How long it takes to get to the grocery store.

Is the sample size big enough? Two cars is definitely not a big enough sample size.

What is the hypothesis? IF you add hot sauce to gasoline, THEN it will make your car go faster.

What is his experimental procedure? Add hot sauce to one car’s gasoline tank but not to the other and see who gets to the grocery store first.

What should Homer’s conclusion be? He might conclude that hot sauce does make a car go faster, but his sample size was not big enough to make a conclusion

Think you’re ready to try some on your own now….?