Introduction: Below, You Will Find the Description of an Experiment

Experiment 1:

Introduction: Below, you will find the description of an experiment. There are flaws in the design of the experiment. Your mission is to find the errors and to suggest how to turn the experiment into one that would fit the definition of a good controlled experiment. You should consider all the characteristics of a good experiment.

Observation: Plants seem to grow faster and taller when they are in the light.

Hypothesis: Light is necessary for green plants to be green.

Experiment: A bean plant growing in sandy soil was kept in the dark for five days. A tomato plant growing in garden soil was kept in the light for five days.

Results: After five days the plant kept in the dark had lost most of its green color and had yellow-colored leaves. The plant kept in the light remained green.

Interpretation: The hypothesis is correct. Experiment 2:

Observation: Detergents are used to wash dishes because the detergent kills bacteria.

Hypothesis: Detergents in water will destroy living things.

Experiment: A teaspoon of detergent was added to an aquarium containing five guppies.

Results: Within three days all the guppies died.

Interpretation: The hypothesis is correct. Experiment 3:

Observation: People who drink water that is polluted seem to become sick.

Hypothesis: If people drink polluted water, they will become ill.

Experiment: A group of three people drank polluted water. Another group of three people drank water that was not polluted.

Results: All three people who drank water that was polluted became ill. None of those who drank unpolluted water became ill.

Interpretation: The hypothesis appears correct, but further investigation is needed. Experiment 4:

Observation: Fewer bird eggs are hatching that in previous seasons.

Hypothesis: If DDT that is used to kill insects gets into the food supply of birds, their eggs with have very thin shells and will break before hatching occurs.

Experiment: 10 different types of wild birds (5 male and 5 female) of the same age, were captured and fed their natural food. The food was sprayed with large amounts of DDT. Another 10 birds of the same types (5 male and 5 female) were captured and fed their natural food without DDT spray.

Results: Three of the female birds fed DDT contaminated food laid eggs with thin shells. Only 1 of the female birds eating food without DDT laid eggs with thin shells.

Interpretation: The hypothesis appears correct. Experiment 5:

Observation: A magazine advertisement claims that a special drink will increase the productivity of workers. The CEO of a company wants to find out if this is true.

Hypothesis: If the workers drink the Special Drink, then they will be more efficient with a simple job such as stapling sets of papers.

Experiment: Fifty workers (Group A) are given the Special Drink and then told to staple a big stack of papers. Fifty other workers (Group B) are NOT given the Special Drink; they are simply told to staple another stack of papers.

Results: After one hour Group A stapled 1,489 stacks of papers and Group B stapled 1,723 stacks of papers.

Interpretation: The Special Drink makes workers less productive. Experiment 6:

Observation: Many people have noticed that their showers are getting covered in a strange green slime. A plumber says that he gets rid of the slime by spraying his shower with coconut juice.

Hypothesis: If showers are sprayed with coconut juice, they will not be susceptible to the dreaded strange green slime.

Experiment: Ten families who live at the beach spray their showers with coconut juice. Ten other families who live in the desert do NOT spray their showers with coconut juice. Three days later, the showers are checked.

Results: Only 2 of the showers at the beach had the strange green slime. None of the showers in the desert had the slime.

Interpretation: Coconut juice can reduce the appearance of the strange green slime in showers. Experiment 7:

Observation: The National Inquirer reported that microwaves appear to increase strength in muscle cells. Several scientists doubt this claim.

Hypothesis: If mice are exposed to microwaves, they will be come extra strong and be able to move a heavy block of wood that prevents them from getting to their food.

Experiment: Ten mice were exposed to microwaves for 10 seconds. Another 10 mice were NOT exposed to microwaves. All the mice were put in cages where large blocks of woods were covering the opening to the food supply.

Results: Eight out of 10 of the microwave-exposed mice were able to push the block of wood out of the way. Only 6 out of 10 of the NON-microwave-exposed mice were able to push the block of wood out of the way.

Interpretation: Microwaves increase muscle strength. Experiment 8:

Observation: A new breath mint with a secret ingredient has appeared in the grocery stores; the mint is called BREATH BUSTER (BB). A scientist wants to test whether this breath mint is really effective or not.

Hypothesis: If people use the new BB breath mints, they will have much better breath than people who do not use BB breath mints.

Experiment: Twenty people were given BB breath mints after eating tasty garlic sandwiches. Twenty other people were given a TIC TAC after eating delicious tuna sandwiches. All people were told that they were getting the BB mints.

Results: 80% of the garlic eaters reported that their breath was fine after using the BB mints. Only 40% of the tuna eaters reported good breath after using TIC TACS.

Interpretation: The secret ingredient in the BB breath mints really works. Experiment 9:

Observation: Seeds sitting in a warm window sill seem to germinate faster than seeds that are kept in a cold room.

Hypothesis: If seeds are exposed to higher temperatures, they will germinate faster that seeds that are exposed to lower temperatures.

Experiment: Ten radish seeds are placed in a dish on a wet paper towel. Ten other seeds are place in another dish on a wet paper towel. One dish is kept at room temperature in the light (24 degrees) and another dish is kept in the dark in an incubator at 34 degrees.

Results: The seeds at 24 degrees germinated in 6 days; the seeds kept at 34 degrees germinated in 8 days.

Interpretation: Plants germinate more quickly at room temperature.