1. A teacher, frustrated with his students’ grades
(sound familiar?), wants to test the effect that the
amount of TV watched per week has on a student’s
grades. He plans on having test groups watch 0, 20, 40
and 60 hours per week for an entire term. Then he will
compare their grades and see if there was a correlation
between the amount of hours spent watching TV and
their grades.
Things that will be held constant in her experiment are:
Testing the same age students
Testing the same track of student (advanced,
standard or basic)
Testing students in the same classes, and with the
same teachers
Students watching the same type of TV shows
a. The independent variable in her experiment will be:
b. The dependant variable will be:
2. A farmer wants to test if the amount of vegetation
(plants) in a field determines how easily the soil can be
eroded. She will test several fields with different
amounts of vegetation to see if there is a difference in
the amount of erosion that takes place over a year’s
time.
a. Will the amount of vegetation in each field be a
constant, independent variable or dependent variable in
her experiment?
b. Is the one-year test period the constant, independent
variable or dependent variable in her experiment?
3. Jacob is an employee of the NFL, assigned the job of
testing footballs to determine how much weight they
can hold before they “pop”. He is going to apply
different weights on top of the footballs to find how
much weight they can support.
He begins his test at around 8 A.M., out on the football
field, testing the footballs with different amounts of
weight. Obviously, Jacob took a long lunch at around
noon and then came back and continued his test,
putting different weights on the ball until each burst,
and how much weight the ball could hold. He tested six
balls and found that football D held the most pressure,
so he reported to the NFL that it was the most durable
ball.
a. What is one unexpected variable that could make
Jacob’s results less than scientifically accurate?
4. Trevor the botanist, as part of his Ph.D. program,
wants to determine if the type of tree determines what
color its leaves will change in the fall. He looked outside
his window and saw a brownish-colored oak. There
were no elm trees around his neighborhood, but he did
see one that was still green while he was in West
Virginia for the football game that Saturday. He also
called his girlfriend, who is Canadian, and she said that
the maple tree in her back yard had turned red. He
wrote in his final paper that the type of tree definitely
determines the color that the leaves will turn in the
autumn.
a. Why did Trevor get a bad grade on his final paper
and not pass his final botany class to get his Ph.D.?
(Hint – what was wrong with his experiment?)
5. Morgan loves the taste of salt, and one day she
wonders how salt affects the density of water.
To test her hypothesis, she plans to put different
amounts of salt in different glasses of water and then
drop a hard-boiled egg in each glass to see if it floats.
a. Is the egg floating/sinking in the water the
responding or manipulated variable in her experiment?
b. Is the amount of salt in the water the responding or
manipulated variable in her experiment?
6. Hailey is a dietician who wants to know whether the
amount of fast food that a person eats would affect their
weight.
Since she is such an EXCELLENT scientist, and she
always follows the scientific method thoroughly, her
first step to answering this problem will obviously be to
conduct a great deal of (a.) __________. And then based
on that information, she then forms a (b.)__________,
which she will design a scientific experiment to test.
7. A construction worker is tired of spending money on
nails, just to find them rusting soon after she buys them.
So…she plans on testing several types of nails to see
which type rusts the fastest.
She places “Nail A” outside and finds that after three
days it is nearly completely covered with rust.
She places “Nail B” and “Nail C” on her dining room
table, one under a heat lamp and one under the regular
light, and finds that neither of them have rust on them
after three days.
She creates a chart and analyzes her results:
Nail Brand:
Results:
Nail A
Rusty
Nail B
No Rust
Nail C
No Rust
a. Which nail (A,B, or C) did her test prove rusts the
fastest? Explain.
8. A famous gemologist (who also wrestles in his spare
time), is paid by a big company that makes saw blades
with diamond tips to determine what size of diamond is
best for cutting metal.
He must design a test to answer this question. The
experiment will test four different-sized diamonds
attached to saw blades and will test how well they each
cut metal.
a. Please help this struggling gemologist, and give him
two constants to be sure to include in his test.
9. The Boy Scouts had some troubles last year in their
Soapbox derby competition…some of the cars weren’t
travelling far enough and couldn’t make it to the finish
line.
The Boy Scouts came to Connor and asked him to
redesign the ramp to maximize speed and distance. He
experimented with different ramp surfaces (such as
metal, wood, felt, carpet) to find which would allow the
cars to travel the farthest.
The independent variable in his experiment was
obviously the different surfaces on the ramp.
a. What was his responding variable?
10. J. Coalmer wants to grow (legal) plants in his
basement and wants to know which type of light is best
to grow them. He recorded his plant growth from last
year, when he used three different lamps and noticed
that each of them produced different sized plants.
He always takes very detailed notes and here is what he
recorded:
Tomatoes
Beans
Corn
Lamp
A
B
C
Height
163 cm
85 cm
301 cm
a. Which lamp obviously makes crops grow the best?
Explain.
11. Shaina has been watching her pet turtles and has
realized a possible connection between the turtle’s shell
size and how fast they are.
Lining up her turtles from smallest shell to largest shell,
she designs a race to find if she was correct.
Her three turtles- Bubbles, Speedy, and Tank – all raced
to the finish line. And, since she is such a good scientist,
she repeated the test numerous times.
a. What was the independent variable in her
experiment?
b. What was the dependent variable?
12. Tucker wants to design an experiment to find what
type of wood produces the most heat when it is burned.
He burns a cord of maple in a fireplace and records the
temperature for an hour. Then, after an hour, he places
a cord of oak on the fire and records the temperature
(and it turns out if was hotter). The third hour, he
places a cord of ash on the fire and records the
temperature (the temp. was the hottest of all).
a. What was the independent variable in this
experiment?
b. Are there any improvements you could suggest to
Tucker to improve his flawed experiment?
13. Lindsey wants to chart a correlation between the
latitude of a location and its temperature. She picks ten
cities at different latitudes and studies their average
temperatures.
She finds that for the most part, the farther from the
equator a city is, the lower its average temperature.
However, one city very near the equator has very low
average temperature.
a. What was the independent variable in this study?
b. Give a possible explanation for the lower
temperatures at that one location near the equator.
14. A scientist wants to test how the color of a T-shirt
affects the amount of heat that it will absorb.
Three different color T-shirts will be tested. For each,
she will put them under a light source for a certain
amount of time with a thermometer and measure their
temperatures.
a. Name three constants that the scientist should use in
her experiment.
15. In order to test which type of bread becomes moldy
faster, Sarah wants to test several types of bread. She
plans on testing them each for a week, in the same
environment, in the same heat, with the same amount of
moisture. It should be a very sound scientific
experiment.
a. The size of the bread that is tested would be the/a:
(Independent variable/dependent variable/constant)
b. The amount of mold on each type of bread after a
week would be the:
(Independent variable/dependent variable/constant)
16. Collin wants to increase his score on Farmville, so
he is designing an experiment to test which fertilizer is
most helpful in growing corn plants.
He plans to test four test groups, each using a different
type of fertilizer. He’ll obviously water them each the
same amount, expose them to the same conditions and
measure the growth after a set period of time.
a. The amount of fertilizer used in the experiment is:
(Independent variable/dependent variable/constant)
b. In one of the four test groups, he plans to use no
fertilizer at all. This would be known as his _________
group.
17. Matthew wants to test the effect of direct and
indirect sunlight on plant growth. He creates an
experiment to test several plants, each receiving
different amounts of direct sunlight. He will water,
fertilize and care for each of his plants the same way
throughout the experiment.
a. What is the manipulated variable in his
experiment?
b. What do you think his hypothesis was?
18. Floyd wants to find out what type of water will
grow the best Grapes (haha). He is going to try growing
grape seeds using all of the same conditions except for
the type of water.
Using 5% saltwater, the seeds did not grow at all.
Using 5% sugar water grew 3 mm in a month.
Using distilled water, the seeds grew 5mm in a month.
a. What was the independent variable in Floyd’s
experiment?
b. What was the dependent variable in Floyd’s
experiment?