LESSON 2 THE SCIENTIFIC METHOD

I. The Scientific Method a. State the question or problem b. Research the problem c. Form a hypothesis- an educated guess, based on research, that is able to be tested d. Design and conduct an experiment e. Record Data and observations f. Analyze data and observations g. Accept or reject the hypothesis based on your findings.

II. Sometimes scientist experiment to find solutions to problems. III. Sometimes discoveries happen accidentally. a. Alexander Fleming discovered penicillin completely by accident. He was running tests on bacterial lawns when “something” landed in his plates and began to kill the bacteria. He investigated to find that the “something” was a Penicillium spore and recognized its medicinal value.

b. Dr. Barnett Rosenberg was working with bacteria and the effect of electric fields on cell division. He found that something in his experiment was halting the cells from dividing but it wasn’t the electric current that he was testing. He later found that a compound now called cisplatin was being formed around the platinum electrodes he was using in his tests. This compound is now used as a drug to stop cell division of some types of cancer cells.

IV. Important things to remember about experiments. a. They must test the hypothesis. b. They must have only one independent and one dependant variable. i. The independent variable is the variable that the experimenter changes in order to see what happens. It is “independent” of anything but the experimenter.

ii. The dependent variable is the variable that changes because of what the experimenter changes. It is “dependant: on the independent variable. iii. The constant is anything in the experiment that does not change. The experiment must be controlled, meaning that only one thing is changed from test group to test group. iv. The control is the test group to which all of the other experimental groups are compared.

c. EXAMPLE: Plant and Aspirin Experiment i.State the Problem: Does aspirin affect plant growth? ii.Research:Look for other plant/aspirin experiments, information about aspirin, information about the types of plants being chosen for the experiment, consult botanists, pharmacists…etc.

iii. Form a hypothesis:“ I believe that plants that are exposed to aspirin will grow better than those which are not” This statement must be based on information that you obtain through your research. iv. Design and conduct an experiment that will specifically test your hypothesis 1. Consider the following points: Independent variable – whether aspirin is added to the plant or not.

2. Dependent variable being measured- height of plant growth. 3. Constants- all other items in the experiment must be exactly the same: same pot sizes, same plant species and source, same water source and amounts, same amount of sunlight, same temperature..etc. 4. Control- the group of plants that is not given any aspirin. 2. Materials needed: a. 10 pots b. 10 red geranium plants c. 1 bottle of 250 mg aspirin tablets d. 1 metric measuring container e. 1 metric ruler f. 1 mortar and pestle

3. Plant the 10 plants in the ten pots in the same manner. 4. Label the pots E-1 through E-5 and C-1 through C Place all 10 pots in the same area, where they will be exposed to the same amount of sun for at least several hours a day. 6. Water each plant with 25ml of water every 3 days, starting with day For plants E-1 –E-5, crush 1 aspirin tablet per plant, and sprinkle on the soil prior to watering. 8. Measure the height of each plant to its highest point once per day, at approximately 5 pm. 9. Continue this experiment for 60 days.

v. Collect Data: vi. Analyze Data: Draw graphs of the data, and explain the trends you see, as well as why you believe these trends occurred. vii. Confirm or Refute your hypothesis: Check your data against your initial prediction, and decide if you were correct or not. Also, list anything which you would do differently, or how you could improve this experiment. List things which could have affected your results (possible errors). Finally, explain what other directions your research could go in.

V. Hypothesis / Theory / and Laws a. Hypothesis is a testable educated guess made by an experimenter about the outcome of an experiment based on knowledge or research. You cannot generate a hypothesis which cannot be tested. b. Theory is a broad generalization that is based on observation, experimentation and reasoning. It explains “what, and why something happens” most of the time. c. Scientific Law is a statement of mathematical expression of some consistency about the behavior of the natural world. It could also be called a rule of nature. d. Technology is the practical use of scientific information. This usually involves making improvements to human life and the world around us.

The steps of the scientific method are repeated until a hypothesis has been supported or discarded

Review Questions: 1. List the seven steps of the scientific method in the correct order. 2. Give an example of the terms independent variable, dependant variable, constant and control. 3. Explain the difference in the terms hypothesis, theory, and law 4. Define technology and give examples involving chemistry. (these are all fair game questions on an exam…hint hint)