Name _____________________________________________________ Date _________ Period ________
Homer notices that his shower is covered in a strange green slime. His friend Barney tells
him that coconut juice will get rid of the green slime. Homer decides to check this this out
by spraying half of the shower with coconut juice. He sprays the other half of the shower
with water. After 3 days of "treatment" there is no change in the appearance of the green
slime on either side of the shower.
What is the Control Group? The side of the shower with water sprayed (to use for
comparison to the coconut juice)
Independent Variable? The spraying of coconut juice. (what are is the experimenter
doing in the experiment?)
Dependent Variable? The amount of slime (what Homer is measuring)
List two constants that Homer should maintain in this experiment The amount of liquid sprayed, the
distance he sprayed, the number of times he sprayed, the temperature, humidity (these are things that
do not change)
What should Homer's conclusion be? Coconut juice does not remove slime from the shower.
Gary is not the smartest snail in Bikini Bottom and believes he can improve his brain power by
eating Super Snail Snacks. In order to test this hypothesis, he recruits SpongeBob and several
snail friends to help him with the experiment. The snails ate one snack with each meal every
day for three weeks. SpongeBob created a test and gave it to the snails before they started
eating the snacks as well as after three weeks.
Based on the data provided, do the Super Snail Snacks work?
Snail
Before
After
Explain your answer.
Gary
64%
80%
They only worked for Gary. All the others score was practically
Larry
78%
78%
the same. Gary was the only one they really helped and that is
probably because he thought they were going to. This a good
Barry
82%
84%
example of bias (the placebo effect) in an experiment. Gary
Terry
72%
70%
though the snacks would make him smarter so he did better on
the test just because he thought he would.
Bart believes that mice exposed to microwaves will become extra strong (maybe he's been
reading too much Radioactive Man). He decides to perform this experiment by placing 10
mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had
not been exposed. His test consisted of a heavy block of wood that blocked the mouse food.
he found that 8 out of 10 of the microwaved mice were able to push the block away. 7 out of
10 of the non-microwaved mice were able to do the same.
Control Group The mice that did not get microwaved (to compare to the mice that were
microwaved)
Independent Variable the amount of microwave radiation (the only difference between the control
group and experimental group)
Dependent Variable The strength of the mice which is measured by moving a block of wood (what Bart
was recording in his experiment)
What should Bart's conclusion be? The microwaving of the mice is not that much of a difference than
the mice that did not go in the microwave. Not a significant difference to say that microwaving had any
effect on the mice. It could have just been a coincidence.
Fry wanted to test which brand of wax was most effective on the ship. He tested four brands
of wax. He measured four equal sections on the hull of the ship. Each of the waxes was used
to cover a section. An equal amount of wax, the same type of rag, and equal buffing were
used. Five drops of water were placed on each square, and the diameter of each drop was
measured (cm) (quantitative). What is the control group? Fry did not have a control
group, what bad science!! If he had one, it would be to have a section of the hull that was
not waxed at all to compare to the sections that were waxed.
The independent variable? The type of wax that Fry used (what he was testing)
The dependent variable? The diameter of each water drop (what was measured)
Two constants that were maintained? Equal sections of the hull, equal amounts of wax, same type of
rag, equal buffing.
After learning about recycling, members of Larry the Cucumber’s biology class
investigated the effect of various recycled products on plant growth. Larry’s lab group
compared the effect of different-aged grass compost on bean plants. Because
composition is necessary for release of nutrients, the group hypothesized that older grass
compost would produce taller bean plants. Three flats of bean plants (25 plants/flat)
were grown for 5 days. The plants were then fertilized as follows: (a) Flat A: 450 g of 3month-old compost, (b) Flat B: 450 g of 6 month-old compost, and (c) Flat C: 0 g
compost. The plants received the same amount of sunlight and water each day. At the
end of 30 days the group recorded the height of the plants (cm).
What is the control group? Flat C because it did not get any compost. It was used to
compare to to the flats that did get compost.
What is the IV? The age of the compost (that was the difference between the two
experimental groups)
What is the DV? The height of the plants (what was measured)
Name two constants in the experiment. Bean plants, grown for 5 days, same amount of compost, same
amount of sunlight and water, same amount of time with fertilizer.
Ten Truffula tree seeds were planted each in 5 pots found around the house that contained 500 g of “Lorax
Potting Soil.” The pots were given the following amounts of distilled water each day for
40 days. Pot 1, 50 mL; Pot 2, 100 mL; Pot 3, 150 mL; Pot 4, 200 mL; Pot 5, 250 mL.
Because Pot 3 received the recommended amount of water, it was used as a control. The
height of each plant was measured at the end of the experiment.
What is the control group? Pot 3 because it received the recommended amount of
water.
What is the IV? The amount of water(what the Lorax was testing)
What is the DV? Height of the plants (was measured at the end of the experiment)
Name two constants in the experiment. Same type of plant, same type of pot, same amount and type of
soil, same type of water (distilled)
Vanessa read that certain perfume esters would agitate bees. Because she did
not want to agitate Barry when he came to her flower shop, she decided to test
four different perfumes to see if they had an effect on the bee’s behavior. She
placed a saucer containing 10 mL of the first perfume 3 m from the hive. She
recorded the time required for the bees to emerge and made observations on
their behavior. After a 30-minute recovery period, she tested the second, third,
and fourth perfumes as well as a saucer of plain water. All experiments were
conduced on the same day when the weather conditions were similar; that is, air
temperature and wind.
What is the control group? The saucer of water was used to compare to the
perfumes.
What is the IV? The type of perfume used (What Vanessa was testing)
What is the DV? Bee’s behavior, but also the amount of time it takes them to
emerge. It is OK to have more than one thing you are measuring, but not ok
to have more than one thing you are testing.
Name two constants in the experiment. Same amount of perfume, same distance from hive, same
saucer, same day/weather conditions.
Tigress wanted to find out if the color of food would affect whether Po
would select it for lunch. She put food coloring into 5 identical bowls
of rice. The colors were plain, red, green, yellow, and blue. Po chose
a scoop of rice of the color of his choice. Tigress did this experiment
100 days in a row. She recorded the number of times Po chose each
type of rice.
What is the control group? The plain white rice (to compare to the
colors)
What is the IV? The different colors of rice
What is the DV? The number of times Po chose each type of rice.
Name two constants in the experiment. Po, identical bowls, same
amount of rice, 100 days in a row, same flavor.
The Smurfs want to put insulation in their new mushroom houses to keep
them warmer. Papa Smurf decided to determine which insulation
transferred the least heat. Smurfette filled each of 6 jars half-full with
water. Brainy sealed each jar with a plastic lid and then they wrapped
each jar with a different kind of insulation. Brainy insisted they leave
one of the jars without any insulation at all. They put the jars outside in
the direct sunlight. Later, they measured the temperature of the water
in each jar.
Why did brainy insist they leave one jar without insulation?
To use as a control group= to compare the other jars to.
What is the IV? The type of insulation
What is the DV? The temperature of the water
Name two constants in the experiment. The amount of water, the starting temp, same jars and same
lids, all in direct sunlight,
Read the following stories. Once you are done determine whether or not each is valid or not based on the
criteria for proper experimentation that were discussed in lecture. You must have at least 2 reasons to
justify your answer. These should be taken from the lecture slide referring to valid science (5 reasons.)
1. One day while in the lab, Mike noticed that one of the rats he had been feeding artificial sweetener to
had a large lump on its back. The next day, he noticed that the rat with the lump and another rat both
died. He immediately called the newspaper and reported that artificial sweeteners cause cancer and
death in lab rats.
Invalid:
He did not repeat his experiment, he did not record or analyze any data, He did not have an
experiment that correlated with his hypothesis. Really the only step he did was observation and
skipped straight to conclusion.
2. Alicia noticed that a plant in her garden didn’t turn brown when the night air became lower then 56
degrees. She though it was because the plant contained enzymes that other plants did not have. She set
up an experiment and tested several plants under different temperature conditions. She was sure to
keep one plant untouched. After she read the results she tried her experiment again and got the same
results. She wrote that her plant did have special enzymes in it to protect it from cold.
Valid:
She only had 1 IV(temperature) and kept everything else controlled and had a control group. She
repeated her experiment to make srue it was right the first time. She collected data and based her
conclusion off the data. Her hypothesis matched the experiment that she did.
3. Lora was hired by the makers of an alcoholic product to test the effects of drinking on animal brain
cells. Lora set up cages of monkeys and had them all drink different levels of alcohol. She recorded the
results of their behavior. After looking at the experiment the first time, Lora concluded that because the
monkeys seemed normal, there were no effects of alcohol on the cells in the monkeys. With this
information, the alcohol company wrote to the government and asked that warning labels be removed.
Invalid:
She did have only one IV and she recorded results. She did not repeat her experiment, but the
experiment is repeatable based on her recording of process and data.
Her hypothesis did not match the experiment (behavior vs. brain cells) and because the one criteria
was not followed the experiment is invalid.
Circle or highlight the correct answer.
1) In an experiment, one _____ is test at a time to determine how it affects results.
A) Control
B) Variable
C) Problem
D) Observation
2) A _____ is the part of an experiment that provides a reliable standard for comparison.
A) Procedure
B) Theory
C) Variable
D) Control
3) A(n) _____ is a suggested solution to a scientific problem.
A) Observation
B) Hypothesis
C) Problem
D) Procedure
4) New observations that do not agree with an accepted theory may cause the theory to be _____.
A) Explained
B) Rejected
C) Proven
D) Changed
5) Although they are the same level of certainty, scientific theories explain _____ while scientific laws
explain_____.
A) Why; how
B) How; why
C) Ideas; facts
D) Facts; ideas