Analyzing Experiments
A group of students in Ohio conducted an investigation during the month of January to study the effects of solar warming. The students used a wooden box painted white. The box was mounted on a post in an open area and a thermometer was fastened on each of the four sides. The box was oriented so that each thermometer faced squarely in a different direction: north, south, east or west. The temperature on each thermometer was recorded in degrees Fahrenheit at 12:00 noon during five consecutive days of clear skies. The picture shows the apparatus used by the students.
The table shows the data collected by the students.
Answer the following questions about this experiment:
1. What problem were these students most likely trying to solve?
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2. What is the independent variable in this investigation?
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3. What is the dependant variable? ______
4. Which variables did the students control?
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5. Is this a controlled experiment? How do you know? ______
6. What pattern(s) or trend(s) do you notice in the data? ______
7. What conclusion can you make from this data? ______
Identifying Variables
For the following experiments determine the independent variable (IV), the dependent variable (DV), at least three controlled variables (CV), and the control group (CG).
1. Different rose bushes are grown in a greenhouse for two months. The number of flowers on each bush is counted at the end of the experiment.
IV ______
DV ______
CV ______
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2. You water three sunflower plants with salt water. Each plant receives a different concentration of salt solutions. A fourth plant receives pure water. After a two week period, the height is measured.
IV ______
DV ______
CV ______
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CG ______
3. Pea plant clones are giving different amounts of water for a three week period. The first pea plant receives 400 milliliters a day. The second pea plant receives 200 milliliters a day. The third pea plant receives 100 milliliters a day. The fourth pea plant does not receive any extra water; the plant only receives natural ways of receiving water. The height of pea plants is recorded daily.
IV ______
DV ______
CV ______
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CG ______
Drawing Conclusions
Circle the letter of the most logical conclusion for each situation below.
1. Nancy tested some common household products with litmus paper. Then, she measured their pH to determine whether each would be classified as an aid, base, or neutral solution. The chart below shows her results:
Item / Blue litmus / Red litmus / pH / ClassificationLemon juice / Turns red / No change / < 7.0 / Acid
Baking soda / No change / Turns blue / >7.0 / Base
Bottled water / No change / No change / 7.0 / Neutral
Vinegar / Turns red / No change / <7.0 / Acid
Based on Nancy’s results, she can conclude that
a. Any substance which does not turn blue litmus paper red is a base.
b. Liquids are always acids.
c. Any substance with a pH more than 7.0 is an acid.
d. The acids in lemon juice and vinegar will turn blue litmus paper red.
2. Based on the graph below, which of the following is the most reasonable conclusion?
a. The more educated a person is, the less likely that person is to smoke.
b. Smoking and education level are not related.
c. People with college educations cannot afford cigarettes.
d. People quit smoking as the get older.
3. The diagram shows the amount of ash blown into the air by five famous volcanic eruptions. The amount of volcanic ash in the eruption cloud is measured in cubic kilometers. The table shows the number of deaths caused by each eruption.
Volcano / Date / Number of DeathsVesuvius / AD 79 / 20,000
Tambora / 1815 / 10,000
Krakatoa / 1883 / 36,000
Mount St. Helens / 1980 / 63
Mount Pinatubo / 1991 / 750
After studying the diagram and table, Scott said, “As the eruption cloud gets larger and larger, more and more people lose their lives.” Do you agree or disagree with Scott’s conclusion? Explain your answer and be sure to give examples.
a) ______
b) ______
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