Chemistry
Mrs. Westphal
Name:___________________
Date:___________________
The Scientific Method
Bad Paint
Imagine that you are the leader of a research team that has been assembled to investigate the complaints of an
automobile dealership. The dealership has sold over a thousand cars in the last six months. Several hundred of
the cars were returned to the dealership because the paint was flaking off. To keep its customers satisfied, the
dealership repainted the cars but is now demanding that the car manufacturer reimburse the dealership for its
costs. The car manufacturer, however, blames the problem on the company that made the paint. The paint
manufacturer claims that none of the other car manufacturers who use their paint has reported any problems.
Your job is to determine who is responsible for the paint problem. You have a sample of paint from the car
manufacturer, a sample of paint from the paint company, and one of the dealership’s painted cars. Use the
scientific method to organize your inquiry.
Questions
1. What observation(s) led the people involved to believe that there was a problem with the paint?
2. Restate this paint problem in the form of a question. Be careful not to make any hypothesis here.
3. List two testable hypotheses that your research team would like to pursue. Remember that your
hypotheses should be consistent with all the information known so far.
4. Describe an experiment that could be performed to test each hypothesis. How could you use the results
to support or refute each hypothesis?
Chemistry
Mrs. Westphal
Name:___________________
Date:___________________
The Strange Case of BeriBeri
In 1887 a strange nerve disease attacked the people in the Dutch East Indies. The disease was beriberi. Symptoms of the
disease included weakness and loss of appetite, victims often died of heart failure. Scientists thought the disease might be
caused by bacteria. They injected chickens with bacteria from the blood of patients with beriberi. The injected chickens
became sick. However, so did a group of chickens that were not injected with bacteria.
One of the scientists, Dr. Eijkman, noticed something. Before the experiment, all the chickens had eaten wholegrain rice, but during the experiment, the chickens were fed polished rice. Dr. Eijkman researched this interesting
case. he found that polished rice lacked thiamine, a vitamin necessary for good health.
1.
State the Problem
2.
What was the hypothesis?
3.
How was the hypothesis tested?
4.
Should the hypothesis be supported or rejected based on the experiment?
5.
What should be the new hypothesis?
How Penicillin Was Discovered
In 1928, Sir Alexander Fleming was studying Staphylococcus bacteria growing in culture dishes. He noticed that a mold called
Penicillium was also growing in some of the dishes. A clear area existed around the mold because all the bacteria that had
grown in this area had died. In the culture dishes without the mold, no clear areas were present.
Fleming hypothesized that the mold must be producing a chemical that killed the bacteria. He decided to isolate this
substance and test it to see if it would kill bacteria. Fleming transferred the mold to a nutrient broth solution. This solution
contained all the materials the mold needed to grow. After the mold grew, he removed it from the nutruient broth. Fleming
then added the nutrient broth in which the mold had grown to a culture of bacteria. He observed that the bacteria died.
6.
Identify the problem.
7.
What was Fleming's hypothesis?
Chemistry
Mrs. Westphal
Name:___________________
Date:___________________
8.
How was the hypothesis tested?
9.
Should the hypothesis be supported or rejected based on the experiment?
10. This experiment lead to the development of what major medical advancement?
Practice Problems
1. Write a hypothesis to explain each of the following observations
a. You notice that the static on your AM radio station increases right before it thunders during a
storm.
b. People who smoke cough more than people who don’t smoke.
c. More people carry briefcases in the airport on Tuesdays than on Saturdays.
2. Two high school friends, Marie and Wendell, buy matching red T-shirts at a rock concert. About a month
after the concert, Marie and Wendell both happen to wear their t-shirts on the same day. Marie notices
Wendell’s shirt is a lighter shade of red. Which of the following hypotheses about the color are testable?
Circle all that apply. (Assume more red t-shirts are available for testing.)
a. Wendell’s t-shirt was lighter than Marie’s t-shirt to begin with
b. Frequent washing of the shirt caused the color to fade.
c. Exposure to the sun caused the color to fade.
3. Albert and Ramon are football teammates. They are also neighbors and walk to school together every
morning. Albert does not eat breakfast and often has to wait for Ramon to finish easting. When football
practice is held after school, Albert and Ramon are close competitors. Every time football practice is held
in the morning, however, Ramon outperforms Albert. Think of a question and a testable hypothesis for
this observation.
Chemistry
Name:___________________
Mrs. Westphal
Date:___________________
4. Sue need to wash the windows in her car, but she didn’t have any window cleaner. Her brother suggested
she use a bottle of ordinary all-purpose ammonia cleaner instead. Much to her surprise, the cleaner did a
great job on the windows. When she was shopping for some window cleaner the next week, she noticed
that most bottles labeled “window cleaner” contain ammonia. Think of a question and a testable
hypothesis for this observation.
Put the following steps of the scientific method in the proper order
________A. Research the problem
________B. Observe and record
________C. Make a hypothesis
________D. Identify the problem
________E. Arrive at a conclusion
________F. Test the hypothesis
Match the following terms with the correct definition.
________1. Hypothesis
a) Organized process used to test a hypothesis
________2. Control
b) An educated, testable guess about the solution to a problem
________3. Variable
________4. Experiment
c) Observations and measurements recorded during an experiment
d) A set of generalized observations of an occurrence in nature
e) A judgment based on the results of an experiment
________5. Conclusion
________6. Theory
________7. Data
________8. law
f)
A logical explanation for events based on a lot of experimentation
g) Used to show that the result of an experiment is really due to the
condition being tested
h) Factor that changes in an experiment