Scientific Method Practice
Review for Unit 1 Exam

A) In 1928, Sir Alexander Fleming was studying bacteria growing in Petri dishes. In some of the dishes he noticed that mold was growing and that a clear area existed around the mold. All the bacteria that had grown in this clear area had died. In the culture dishes without the mold, no clear areas existed. Fleming hypothesized that the mold must be producing a chemical that killed the bacteria and decided to do an experiment to see if it was true. To do this, Fleming transferred the mold to new Petri dishes and added to it some bacteria. He observed that the bacteria died. In a different Petri dish, Fleming just added bacteria (no mold). The bacteria in this dish did not die. Fleming concluded that the mold produced a bacteria-killing substance. He called the substance that killed the bacteria penicillin.

  1. Name an observation that Fleming made while doing his experiment.
  2. Identify the problem/question that Fleming wanted to solve.
  3. Create a hypothesis that Fleming could have used to solve his problem.
  4. In Fleming’s experiment, state which group was the control group?
  5. In Fleming’s experiment, what would be the dependent variable?
  6. What was Fleming’s conclusion?
  7. Do Fleming’s data and conclusion support his hypothesis? Why or why not? Explain.

B) Joe is the captain of a motorcycle racing team. He is hoping the riders on his team will get better times if he uses an additive in the fuel. He decides to try it out during practice runs. He gives half of his team the fuel they’ve been using all season up until now. He gives the other half of hi his team the fuel with the additive. He clocks how quickly they can get around the course and the average temperatures of the bikes’ engines. Joe then compares times and temperatures between the two groups.

1.  Write a problem or purpose statement for this informal experiment.

2.  What is the control group for this experiment?

3.  What is the experimental group in this experiment?

4.  What is the variable?

5.  Why shouldn’t Joe try changing more than one thing at a time between the two groups (like fuel, tires, helmets, etc)?

6.  What is the independent variable in the experiment?

7.  What is the dependent variable(s) in the experiment?

8.  Write a hypothesis for the experiment based upon the information above.

C) Ten seeds were planted in each of five pots found around the house. Each pot contained 500g of “Pete’s Potting Soil”. The pots were given the following amounts of distilled water each day for 40 days: Pot 1, 50ml; Pot 2, 100ml; Pot 3, 150ml; Pot 4, 200ml; Pot 5, 250ml. Because pot 3 received the recommended amount of water, it was used as the control. The height of each plant was measured at the end of the experiment.

  1. Identify the IV, the levels of the IV, the DV, the number of trials, constants and the control (if present).
  2. Identify the hypothesis for the experiment. If one is not explicitly stated, write one for the scenario.
  3. Set up a graph onto which the results could be plotted.
  4. State at least two ways to improve the experiment as described.

D) Gloria wanted to find out if the color of food would affect whether kindergarten children would select it for lunch. She put food coloring into four identical bowls of mashed potatoes. The colors were green, red, yellow and blue. Each child chose a scoop of potatoes of the color of their choice. Gloria did this experiment using 100 students. She recorded the number of students that chose each color.

  1. Identify the IV, the levels/units of the IV, the DV, the levels/units of the DV, the number of trials, constants and the control (if present).
  2. Identify the hypothesis for the experiment. If one is not explicitly stated, write one for the scenario.
  3. Set up a graph onto which the results could be plotted.
  4. State at least two ways to improve the experiment as described.

E) Esther became interested in insulation while her parent’s new house was being built. She decided to determine which insulation transferred the least heat. She filled each of five jars half-full with water. She sealed each jar with a plastic lid. Then she wrapped each jar with a different kind of insulation. She put the jars outside in the direct sunlight. Later, she measured the temperature of the water in each jar.

  1. Identify the IV, the levels/units of the IV, the DV, the levels/units of the DV, the number of trials, constants and the control (if present).
  2. Identify the hypothesis for the experiment. If one is not explicitly stated, write one for the scenario.
  3. Set up a graph onto which the results could be plotted.
  4. State at least two ways to improve the experiment as described.