Practice Test
Scientific Investigations
1. Scientific inquiry attempts to search out, describe, explain, and predict things that happen in
nature. Which of the following best describes how progress is made in scientific inquiry?
A. by researching the history of science and learning about scientific progress in the past
B. by asking questions and collecting, analyzing, and interpreting data to answer them
C. by asking questions and researching the answers in papers, books, and on the internet
D. by asking questions and collecting, analyzing, and interpreting different people's opinions
Scientific Investigations
2. Peter wants to figure out which insects have 4 legs, 6 legs, and 8 legs. He decides to do this by
A. performing experiments on several types of insect legs.
B. collecting several types of insects and counting the number of legs.
C. making a model of an insect and counting the number of legs.
D. trying to remember how many legs each type of insect has.
Scientific Investigations
3. The children in Ms. Murray's class have to perform an investigation. The question their study
must answer is "How do various types of plants differ in their physical features?"
What type of investigation must the children do?
A. do an experiment on the chemical components of plants
B. observe and record physical characteristics of plants
C. make a model of a plant, since they are hard to observe
D. find several new species of plants
Scientific Investigations
4. Maria hypothesizes that the amount of light in an environment affects the growth of algae
living in that environment.
Which of the following is the best type of investigation for Maria to perform in order to test her
hypothesis?
A. observe algae in nature
B. conduct a controlled experiment
C. build a computer model of algae growth
D. collect and observe different specimens of algae
Scientific Investigations
5. Henry is interested in studying the different techniques perching birds use to build their nests.
What type of investigation would best help Henry learn more about this topic?
A. discover a previously unknown perching bird species
B. make observations in nature
C. perform a controlled experiment
D. build a model of a nest
Scientific Investigations
6. A scientist wants to publish a report on general feeding habits of moose in Canada. He should
A. study in only one location but observe as many moose as possible.
B. observe as many moose as he can in as many locations as possible.
C. observe just one moose but study it for the rest of its life.
D. study in as many locations as possible but observe only one moose in each location.
Scientific Investigations
7. Oscar placed a beaker of water on a hot plate and recorded the temperature of the water for
four minutes. He recorded his observations in the data table below.
Time (s) Temperature (°C)
0
24
Observations
no activity</td
30
35
no activity</td
60
57
some steam rising</td
90
81
more steam rising;
tiny bubbles forming</td
120
98
more steam rising;
more bubbles</td
150
100
boiling</td
180
100
boiling</td
210
100
boiling</td
240
100
boiling</td
Based on Oscar's observations, what is the most appropriate scientific question to ask?
A. Why does the temperature of the water continue to rise while it boils?
B. Why does the temperature of the water remain constant while it boils?
C. What causes the temperature of the water to decrease over time?
D. Does water boil because the temperature is being observed?
Scientific Investigations
8. The following chart presents sixteen sets of measurements of the pressure vs temperature for
Abilene, TX, taken over a period of four days.
Air Pressure & Temperature for Abilene, TX
Temperature (°F) Pressure (mb)
50
1009.9
53
1009.0
55
1008.8
56
1008.7
58
1008.4
62
1007.3
68
74
75
76
78
79
1006.4
1005.3
1004.8
1004.2
1003.8
1003.5
Which of the following is a scientific question that this data can answer?
A. Is the weather nice in Abilene, TX?
B. Does pressure increase when the temperature rises?
C. What was the highest temperature in Abilene over the four days shown?
D. Why does pressure change?
Scientific Investigations
9. Scientific questions can be asked based on _______.
A. scientific investigation
B. observations
C. previous research
D. all of these
Scientific Investigations
10. Dr. Grey performed an experiment to test how temperature affects activity levels in mice.
She put one group of mice in a cold environment and another group of mice in a hot
environment.
Everything else about the two environments was the same, including the type and amount of
food and water. She allowed the experiment to last for a few generations of mice and tested the
activity levels of the different groups.
There was no change in the activity levels of the mice, but she noticed that the mice in the cold
environment had much darker, thicker fur than the mice in the hot environment. What scientific
question could she ask based on her results?
A. Do the mice in the cold environment run faster than the mice in the hot environment?
B. Does temperature have an effect on fur color and thickness in mice?
C. Which group of mice is the most attractive?
D. Does food type have an effect on fur color and thickness in mice?
Scientific Investigations
11. George is interested in spiders. He wants to study why spiders spin webs, so he comes up
with the following question: Do spiderwebs help spiders catch prey?
George's question is
A. not a valid scientific question because it is not testable.
B. a valid scientific question because it is testable.
C. not a valid scientific question because it is not about science.
D. not a valid scientific question because it asks about an opinion.
Scientific Investigations
12. The soil around Jack's house is very sandy. Whenever it rains, the ground dries out quickly.
While spending the summer at his grandmother's house, Jack notices that the ground stays wet
for a long time after it rains. Jack digs in his grandmother's yard in several places and finds that
the soil has a lot of clay in it. He wonders if the observed differences in soil between his house
and his grandmother's house cause the moisture differences.
To investigate this problem, which of the following questions should Jack ask?
A. Is there any organic matter in either of the two soils?
B. Will a sample of water flow through a volume of sandy soil faster than through an equal
volume of clay-rich soil?
C. Will a sample of sandy soil from Jack's house mix well with a sample of clay-rich soil
from his grandmother's house?
D. Why are the particles found in the two soils different?
Scientific Investigations
13. Annabelle loves to learn about plants. For a class project, she thought of the following
question:
Do plants enjoy it when people sing to them?
This question is
A. not a valid scientific question because it is about plants.
B. not a valid scientific question because it is not testable.
C. a valid scientific question because it is about plants.
D. a valid scientific question because it is testable.
Scientific Investigations
14. Glenn formulated the following question that he wanted to use for a scientific investigation:
How many planets are in the nearest galaxy?
Is this a valid question for use in Glenn's scientific investigation?
A. Yes; it is testable.
B. No; it is not testable.
C. No; it is not connected to science.
D. Yes; it is connected to science.
Scientific Investigations
15. After investigating many properties of gases, Darren hypothesized that the volume of a gas is
related to its temperature. Which of the following observations led to his hypothesis?
A. A balloon filled with air expanded when it was heated and shrank when it was cooled.
B. A syringe filled with air could be compressed when he applied pressure to the plunger.
C. All of the gases that were investigated were both odorless and colorless.
D. all of these
Scientific Investigations
16. Which of the following statements is true regarding scientific hypotheses?
A. There are no valuable hypotheses.
B. A testable hypothesis is valuable, even if evidence shows that it is false.
C. A testable hypothesis is valuable only if all evidence supports it.
D. Every hypothesis is valuable, whether or not it is testable.
Scientific Investigations
17. Tom is curious about what causes iron to rust. Which of the following sentences is the best
hypothesis for Tom to test?
A. Rust doesn’t look like iron because it is a different color.
B. Iron reacts with water to form rust.
C. Why does iron rust?
D. Something causes iron to change into rust.
Scientific Investigations
18. Ava observes that a certain species of bird follows behind a herd of cattle. The bird species
primarily eats insects. The birds stay with the herd of cattle as they graze.
What is a scientific hypothesis that Ava could formulate based on her observations?
A. The birds are happier around big herds of cattle rather than small herds.
B. The birds follow the herd because the cows stir up insects for the birds to eat.
C. Why does this species of bird follow herds of cattle?
D. Do the birds get any benefit from following the herd of cattle?
Scientific Investigations
19. A hypothesis is
A. a summary of events written in a particular fashion.
B. a statement that proposes a possible explanation to some phenomenon or event.
C. the result of a scientific experiment performed for the purpose of proving a theory.
D. the process of experimentation designed specifically to disprove a scientific theory.
Scientific Investigations
20. A hypothesis is best described as
A. a detailed list.
B. an educated guess.
C. a summary.
D. a conclusion based upon evidence.
Scientific Investigations
21. Which of the following sentences is the best example of a hypothesis?
A. How many types of organisms are there?
B. UV radiation does not cause skin cancer.
C. Chickens lay more eggs when they are happy.
D. Why does the Earth orbit around the sun?
Scientific Investigations
22. Jobi read in his science textbook that when a laser is shined into a diamond in a dark room,
the diamond will scatter the light, throwing many separate, focused beams of light on the walls
and ceiling. Jobi hypothesized that any clear, cut stone would have the same effect on a laser. He
collected samples of quartz and tried it out, but the quartz did not have the same effect.
Jobi decided that his hypothesis and experiment were a waste. Was Jobi correct about this?
A. Yes; spending time on an experiment that fails is a waste.
B. No; hypotheses are valuable whether or not they are correct.
C. Yes; he chose an untestable hypothesis.
D. No; his hypothesis was useless, but his experiment was valuable.
Scientific Investigations
23. A scientific theory is a well-tested explanation for a wide range of observations or
experimental results. A hypothesis is a possible answer to a question. When does a hypothesis
become a scientific theory?
A. after the hypothesis is first formed by a scientist
B. after the hypothesis has been confirmed through extensive testing
C. after a hypothesis is shown to be correct in one experiment
D. after a competing hypothesis has failed testing
Scientific Investigations
24. Astronomers have observed that the universe is expanding and is accelerating in all
directions. Using this evidence, astronomers have hypothesized that a huge explosion called the
big bang created the universe. Which of the following correctly describes the big bang?
A. none of these
B. theory
C. fact
D. opinion
Scientific Investigations
25. Major scientific theories include the cell theory, the big bang theory, and the theory of plate
tectonics. How are scientific theories formed?
A. through a single scientific discovery in which a scientist learns something new
B. through extensive testing and the accumulation of several lines of evidence
C. through the formation of several related hypotheses
D. through meetings between scientists in which they discuss several possible answers to a
scientific question
Scientific Investigations
26. Isabella's next door neighbor has a theory that the best time to wash your car is late in the
afternoon on Sunday. Is this a scientific theory?
A. No, it is better to wash cars on Saturday.
B. No, it is an opinion and is not testable.
C. Yes, the car will stay clean for more of the week.
D. Yes, the neighbor might be a scientist.
Scientific Investigations
27. In ancient times, many people believed in a geocentric model of the solar system, where the
Earth was the center of the system. During the 16th and 17th centuries, men such as Copernicus,
Kepler, and Galilei theorized or found evidence that the Sun was actually the center of the solar
system. However, despite convincing evidence, this idea was not accepted until some time later.
Why was this idea not initially accepted?
A. There was no evidence published supporting their ideas.
B. It is difficult to change a commonly held belief.
C. The Sun is not large enough to be at the center of the solar system.
D. After a theory has been around for one hundred years, it cannot be changed.
Scientific Investigations
28. Sometimes scientists gather information that contradicts accepted theories or explanations. If
the new information is replicated many times, the accepted theory that it contradicts will often be
updated or modified to reflect the new information.
Based on this, it can be determined that scientific knowledge is durable in part because
A. scientists ignore information that contradicts accepted theories.
B. it is open to change as new information is learned.
C. new information on accepted theories is never discovered.
D. experiments are never performed more than once.
Scientific Investigations
29. Scientific experiments often produce new scientific knowledge.
What usually happens if a scientific experiment generates new knowledge that doesn't agree with
an existing theory?
A. Science is abandoned as a way to generate knowledge.
B. The new knowledge is used to reevaluate the theory.
C. The new knowledge is ignored in favor of the old theory.
D. Scientists choose whichever side seems to have the most followers.
Scientific Investigations
30. For most of the first 1,800 years in the common era, most people, including scholars, did not
believe in sexual or asexual reproduction for many organisms. They thought many creatures,
including frogs and mice, came from nonliving things. This was the theory of spontaneous
generation. For example, maggots were believed to simply appear in meat as it spoiled. Today
we know that maggots come from eggs that were laid on or in the meat by their mothers.
Louis Pasteur proved that living organisms do not just appear. Broth that is left sitting out for a
while will grow cloudy as small organisms live and grow in it. Louis Pasteur boiled broth and let
it cool without coming into contact with any "particles" in the air. Broth treated that way did not
grow cloudy.
Louis Pasteur's experiment showed that small organisms that live in broth do not come from the
broth itself. Which of the following best describes this statement and how it changed what
scientists know?
A. It is a set of detailed observations of how single-celled organisms live and reproduce.
B. It is a scientific observation that goes against the theory of spontaneous generation, so the
theory must be wrong.
C. It is a scientific theory of how life begins that fits the facts better than spontaneous
generation.
D. It is a result that was predicted by the theory of sexual reproduction, proving that theory to
be correct.
Experimental Design
31. How do the independent and dependent variables in an experiment compare?
A. The independent and dependent variables are the exact same as each other.
B. The independent variable controls the dependent variables.
C. The dependent variable controls the independent variables.
D. The independent and dependent variables have no effect on each other.
Experimental Design
32. Arthur reads an article describing an experiment to test the effects of caffeine on the reaction
time of humans—how long it took them to respond to a particular signal. In the experiment, the
subjects' reaction times were measured, then they were divided into three groups. One group was
given a high dose of caffeine. The second group was given a medium dose of caffeine. The third
group was given a sugar pill that had no caffeine. After waiting 45 min for the caffeine to take
effect, the reaction times were measured again.
In the experiment Arthur read about, what was the dependent variable?
A. the type of signal each person responded to
B. the change in reaction times for each person
C. the amount of caffeine given to each person
D. the amount of time the caffeine was given to take effect
Experimental Design
33. The observed results of an experiment that occur from changes in the independent variable
are known as _______.
A. trials
B. dependent variables
C. controlled variables
D. constants
Experimental Design
34. In a controlled scientific experiment,
A. no variables are kept constant.
B. one or more variables are kept constant.
C. all variables are kept constant.
D. only one variable can be kept constant.
Experimental Design
35. Omar wants to determine if the mass of a model rocket affects how long the rocket is able to
stay up in the air. To do this, he constructs three identical rockets and then fills two of the rockets
with varying amounts of sand to add mass. He then launches the rockets one at a time and times
how long they are able to stay airborne.
What is the independent variable in Omar's experiment?
A. the force with which each rocket is launched
B. the masses of the model rockets
C. the time the rockets remain airborne
D. the materials out of which the rockets were made
Experimental Design
36. Lexi is researching crime rates. She is trying to make a conclusion about whether the crime
rate changes with the population in each county in her state. What is the dependent variable of
her investigation?
A. the state
B. the crime rate
C. the population
D. the county
Experimental Design
37. Aisha wonders whether wind or water causes the most erosion. She set up an experiment in
which she used a watering can to pour water down a pile of dirt. She then used a fan to blow
wind on a second pile of dirt that is the exact same shape and size as the first pile of dirt. Aisha
then measured how the height of the dirt piles changed. She also drew pictures of how their
shape changed. In this experiment, what was the dependent variable?
A. the tools used to measure the dirt piles
B. the height and shape of the dirt piles
C. the agent of erosion applied to the dirt piles
D. the time the dirt piles were eroded away
Experimental Design
38. Walter learned in science class that different substances release heat at different rates. He
decides to test this.
At home, Walter turns the oven to 200°F. He places three casserole dishes in it: one is made of
metal, one is made of glass, and one is made of ceramic. He leaves them in the oven for an hour.
He then removes them from the oven, places a single ice cube on each one, and times how long it
takes the ice cube to melt.
In this experiment, what is the independent variable?
A. the volume of each ice cube
B. the material each pan is made of
C. the amount of time it takes for the ice to melt
D. the temperature of each pan
Experimental Design
39. Jose wants to know the effects of mass, force, and surface type on the motion of a small box.
He has one spring, one box, and an assortment of weights to put in the box. He compresses the
spring between the box and a wall, measures how far he has compressed it, then releases the box.
He then measures how far the box travels before stopping. The table below presents the data he
collected.
Compression
of spring
mass
of box
type of
surface
0.5 cm
500 g
carpet
34 cm
1.5 cm
250 g
carpet
199 cm
0.5 cm
300 g
linoleum
239 cm
1.5 cm
450 g
linoleum
477 cm
0.5 cm
250 g
concrete
123 cm
1.5 cm
300 g
concrete
305 cm
What did Jose do wrong?
distance
traveled
A. He did not graph his data.
B. He changed more than one variable at a time.
C. He did not identify all the variables in the experiment.
D. He measured the wrong variable.
Experimental Design
40. Sarah has a garden that she waters by hand. Some of her garden is shaded by trees. Sarah
wants to know where in her garden she should plant chamomile. She decides to conduct an
experiment on some chamomile plants to find out.
Which of the following variables should Sarah change?
A. the type of chamomile plants she uses
B. how much sunlight the chamomile gets
C. the height of the plants
D. how much water she gives the plants
Experimental Design
41. The factors that are kept the same throughout an experiment are called the _______.
A. data
B. constants
C. variables
D. samples
Experimental Design
42. Julian designs an experiment to see how well different liquids lubricate wooden surfaces. He
sets up a number of identical wooden ramps and prepares to slide identical wooden blocks down
them. He will time how long it takes each block to reach the end of the ramp. He covers one
ramp with water, the second with motor oil, and the third with corn syrup.
What can Julian use as a control group for the experiment?
A. a second set of ramps covered with water, oil, and syrup respectively
B. a ramp with no liquid on it
C. a block that drops straight down instead of sliding down a ramp
D. a ramp with no friction on its surface
Experimental Design
43. Which of the following should be done when designing an experiment for a controlled
scientific investigation?
A. plan the variables
B. list the procedures
C. list the needed materials
D. all of these
Experimental Design
44. Jack is planning an experiment to see how temperature can affect the reproduction rate of a
certain species of bacteria.
Jack is listing some of the variables that could affect the outcome of the experiment. Which of
the following variables should be included on his list?
A. food Jack eats, day of week, number of pages in log book
B. temperature, light level, species of bacteria
C. time of year, clothes Jack wears, Petri dish mass
D. time of day, color of walls in lab, Jack's height
Experimental Design
45. Julia wants to find out which color fabric will heat up the fastest when put under a direct
light.
So, she places pieces of red, white, and green fabrics outside in the sunlight. Then, she places
pieces of black, yellow, and blue fabric inside under a bright lamp. Finally, she measures the
temperature of all the fabric samples every 5 minutes.
Will Julia's results be valid?
A. Yes, all scientific investigations are valid.
B. No, she has more than one independent variable.
C. Yes, she is conducting a controlled experiment.
D. No, she should only test one color of fabric at a time.
Experimental Design
46. Ned is designing an experiment to test which hand sanitizer kills the most E. coli bacteria. In
order for Ned's results to be valid, what must he do?
A. test each hand sanitizer on different days and at different times of the day
B. test the hand sanitizers on bacterial colonies that are kept in the exact same environmental
conditions, such as temperature and light level
C. test the first brand of hand sanitizer on E. coli bacteria, then test the second brand of hand
sanitizer on a sterilized Petri dish
D. test the hand sanitizers first on E. coli bacteria and then on other bacterial species
Experimental Design
47. Beth wanted to find out whether or not salt affects how quickly ice melts. She used an ice
cube tray to make 10 ice cubes of the same shape and size. Then, she placed the ice cubes on the
same windowsill. She sprinkled each ice cube with one teaspoon of salt, and timed how long it
took for the cubes to melt. She recorded all of the data.
If someone else read the data, would he or she be able to make an accurate conclusion about the
effect of salt on ice?
A. No, because Beth should have used a different amount of salt on each of the ice cubes.
B. No, because the data does not show how quickly the ice would have melted without the
salt.
C. Yes, because using 10 ice cubes gives enough trials for the results to be accurate.
D. Yes, because Beth used only one independent variable and everything else was the same.
Experimental Design
48. Jordan wants to conduct an experiment to see if plant food makes a difference in how well
plants grow. He gets 10 pots and plants a different type of seed in each. He gives plant food to
half of the plants and does not give plant food to the rest. He records the amount of plant food
given to the plants. But, he decides not to write down the types of seeds he planted.
Will someone else be able to repeat the experiment and find reliable results?
A. No, the results would not be reliable since not all of the plants were given plant food.
B. No, because Jordan should have used the same type of seeds in each pot, and should have
recorded the type of seeds.
C. No, because Jordan would need to use all vegetable seeds for the experiment to be
reliable.
D. Yes, because the type of seed is not important. As long as some of the plants are receiving
plant food and some are not, the experiment will give the same results.
Experimental Design
49. Javier has found a beetle during a field study. He suspects that it might be a new species of
beetle that no one has ever documented before. He takes the beetle back to his lab and examines
it under a microscope.
What does Javier need to do so that he can accurately compare his beetle to known species of
beetle?
A. Javier must carefully record and describe the beetle's response to laser light.
B. Javier must carefully record and describe all of the characteristics of his beetle.
C. Javier must collect some of the beetle's tissue so it can be cloned.
D. Javier must compare the beetle's foot speed to that of an ant.
Experimental Design
50. Selma hypothesizes that the mass of a sample of water will not change if it is frozen. She
conducts an experiment to test her hypothesis. Her experimental steps are as follows:
1. Fill a beaker with 500 mL of water.
2.
3. Place the beaker in the freezer.
4. After the water freezes, place the beaker on the balance and
measure its mass.
Which of the following steps is missing from Selma's experiment?
A. Use a thermometer to measure the water's temperature.
B. Place the beaker on the balance and measure its mass.
C. Set a timer for 2 hours.
D. Run the water through a filter to make sure there are no impurities in it.
Experimental Design
51. Nick hypothesizes that wax has a higher melting point than chocolate. How can Nick test his
hypothesis?
A. Heat samples of wax and chocolate and use a stopwatch to time how long it takes until
they start to melt.
B. Heat equal masses of wax and chocolate and measure their temperatures when they start to
melt.
C. Measure the volume and weight of samples of wax and chocolate and calculate their
densities.
D. Use Mohs Hardness Scale to test how easily wax and chocolate can be scratched.
Experimental Design
52. Jamal needs to know how fast a red oak sapling grows. What can he do to find this out?
A. Ask his friends to find out if any of them have seen a sapling grow.
B. Grow a sapling from seed and measure its growth periodically.
C. Cut down an adult red oak and count its rings.
D. Measure how fast the saplings of different kinds of oaks grow.
Experimental Design
53. Gabriel wants to find out what the melting point of wax is. He has a block of wax, a
graduated cylinder, a pan, a thermometer, and scales. Which is the best procedure to follow for
the experiment?
A. Measure the wax's temperature. Then heat it until it melts and weigh it on the scales.
B. Place the wax in the pan and heat it until it starts to melt. Then measure its temperature.
C. Place the wax in the pan and heat it until it melts. Then pour the wax into the graduated
cylinder and measure its volume.
D. Weigh the wax with the scales. Then heat it until it melts and weigh the wax a second
time.
Experimental Design
54. Kyle is investigating how the motion of a football thrown through the air is affected by the
ball's initial speed. The data for his first trial are shown below.
Projectile
Mass
(kg)
Angle of
Release
Force
Applied (N)
Direction of
Wind
Wind
Speed
(m/s)
Distance
Traveled (m)
football
0.43
20°
450
northwest
19
16
For Kyle's next trial, which factor must he change to continue his investigation?
A. the angle of the ball's release
B. the force applied to the ball
C. the direction of the wind
D. the wind's speed
Experimental Design
55. A scientist wants to determine which fertilizer is more effective—Fertilizer X or Fertilizer Y.
The best way for her to proceed would be to design an experiment with
A. two groups of plants—a group fertilized by Y and a control group with no fertilizer.
B. three groups of plants—a group fertilized by X, a group fertilized by Y, and a control
group with no fertilizer.
C. three groups of plants—a group fertilized by X, a group fertilized by both X and Y, and a
control group with no fertilizer.
D. two groups of plants—a group fertilized by X and a control group with no fertilizer.
Experimental Design
56. Anna is conducting an experiment to determine how weather affects cell phone reception.
She is trying to decide the best way to conduct her experiment in order to collect meaningful
data.
Which of the following experiments would help Anna collect the best data?
A. Test different cell phones in different locations on days with rainy weather.
B. Test a cell phone's reception in the exact same location under various atmospheric
conditions.
C. Test different cell phones in different locations on days with clear weather.
D. Test a cell phone's reception in one location with clear weather and in another location
with rainy weather.
Experimental Design
57. Anna is conducting an experiment to determine how weather affects cell phone reception.
She is trying to decide the best way to conduct her experiment in order to collect meaningful
data.
Which of the following experiments would help Anna collect the best data?
A. Test a cell phone's reception in the exact same location under various atmospheric
conditions.
B. Test different cell phones in different locations on days with rainy weather.
C. Test different cell phones in different locations on days with clear weather.
D. Test a cell phone's reception in one location with clear weather and in another location
with rainy weather.
Experimental Design
58. A student would like to determine how heating a liquid changes its volume. The student
hypothesizes that the liquid will increase in volume. The following list shows the steps taken by
the student in order to test the hypothesis.
I.
II.
III.
IV.
V.
Select the liquid to test.
Place the liquid in a sealed container.
Use a Bunsen burner to heat the liquid by 10°C.
Measure the volume of the liquid.
Record the results.
What is wrong with how the student conducted the investigation?
A. The student should have increased the temperature of the liquid by more than 10ºC.
B. The volume of the liquid should be measured before it is heated.
C. The length of time it took for the liquid to be heated should be measured.
D. The hypothesis was not valid because it is impossible for liquids to change in volume.
Experimental Design
59. David is doing an investigation about factors that affect plant growth, so he plants two young
elm trees near each other in his garden. He gives the first elm tree a gallon of water every week,
and he gives the second elm tree fertilizer once a month.
He plans on measuring the trees' heights and trunk girths every week for the next year. How can
David best improve his investigation?
A. do not measure the trees growth at all until a full year has passed
B. test only one independent variable at a time
C. use cedar trees instead of elm trees for the investigation
D. place both trees in a greenhouse instead of his garden
Experimental Design
60. Jenny dissolves as much salt as she can in 100 mL of room-temperature water. She learned in
class that less salt will dissolve in cold water than in hot water. Jenny adds some ice to the salt
water and observes what happens.
What effect will adding the ice to the solution have on the amount of salt that can be dissolved
into it?
A. The ice will have no net effect on the amount of salt that can be dissolved in the solution.
B. The effect is unpredictable because the ice changes two variables at the same time.
C. It will force some of the salt to leave the solution because it will decrease the temperature.
D. It will allow more salt to be added to the solution because it adds water to the solution.
Answers
1. B
2. B
3. B
4. B
5. B
6. B
7. B
8. B
9. D
10. B
11. B
12. B
13. B
14. B
15. A
16. B
17. B
18. B
19. B
20. B
21. B
22. B
23. B
24. B
25. B
26. B
27. B
28. B
29. B
30. B
31. B
32. B
33. B
34. B
35. B
36. B
37. B
38. B
39. B
40. B
41. B
42. B
43. D
44. B
45. B
46. B
47. B
48. B
49. B
50. B
51. B
52. B
53. B
54. B
55. B
56. B
57. A
58. B
59. B
60. B
Explanations
1. Scientific inquiry progresses by constantly asking questions and collecting, analyzing, and
interpreting data in order to answer them. Researching something in books, articles, and on the
internet is a good way to learn, but it can only teach what someone else has already figured out.
To make new discoveries, new questions must be asked and answered with objective data.
2. In order to figure out how many legs different insect species have, Peter should collect several
types of insects and count the number of legs.
This will let Peter figure out the number of legs each bug has, while making a model, trying to
remember facts, and performing experiments on insect legs will not be helpful in the
investigation.
3. An investigation dealing with differences in the physical features of plants could be studied by
observing and recording the physical characteristics of plants.
Plants are easy to grow and observe in nature, so a model would not be necessary.
Finding new plant species is not needed, since most physical features of plants are shared among
species (leaves, roots, flowers, etc.).
Also, experimenting on the chemical components of a plant would not tell anything about the
physical features.
4. Different scientific questions and hypotheses require different types of scientific
investigations. Some questions, such as questions involving how one factor affects an organism
or event, can be answered through controlled experiments. Other questions can be answered
through collecting specimens, building models, and/or making observations.
5. Different scientific questions and hypotheses require different types of scientific
investigations. Some questions can be answered through controlled experiments. Other questions
can be answered through collecting specimens, building models, and/or making observations.
A question regarding animal behavior can be best answered by making observations in nature.
6. In order to write a report about general feeding habits of moose over such a large area as
Canada, the scientist needs to observe as many moose as he can in as many locations as
possible. Studying too few moose or in just one location will not provide enough data to apply
his results to all moose in Canada. The scientist can also use studies by other scientists to help in
his report.
7. Based on Oscar's data, the temperature of the water continued to rise until the water began to
boil. As the water boiled, the temperature remained constant at 100°C.
Therefore, the best question to ask is, "Why does the temperature of the water remain
constant while it boils?"
8. The question "Why does pressure change?" only asks "why?"
The question "What was the highest temperature in Abilene over the four days shown?"
identifies only one variable: temperature.
The question "Is the weather nice in Abilene, TX?" asks about something that cannot be
measured: how nice the weather is.
Only the question "Does pressure increase when the temperature rises?" is a specific question
that names at least two variables and can be answered by the given data.
9. Scientific questions can be based on observations, previous research, or scientific
investigation.
10. Dr. Grey's experiment showed that the mice raised in the cold environment had thicker,
darker fur than the mice raised in the hot environment. Based on this observation, Dr. Grey could
next ask: "Does temperature have an effect on fur color and thickness in mice?"
11. A scientific question must be testable and can be answered using data and facts obtained
from research, observations, or experiments. It cannot be used to ask about opinions or emotions.
"Do spiderwebs help spiders catch prey?" is a valid, testable scientific question.
12. Jack wonders if the observed difference between the soils' particle size relates to the moisture
each soil can hold. To investigate this, he could determine whether a sample of water would
flow through a volume of sandy soil faster than through an equal volume of clay-rich soil. If
water flows faster through sandy soil than it does through clay-rich soil, this could explain why
the ground at Jack's house dries out faster than the soil at his grandmother's house.
13. Good scientific questions must be testable, and they can be answered using data and facts
obtained from research, observations, or experiments. Good scientific questions do not ask about
opinions or emotions.
"Do plants enjoy when people sing to them?" is not testable because it is not possible to ask a
plant whether it enjoys something or not. Therefore, Annabelle's question is not a valid
scientific question.
A possible, valid scientific question on this topic is "Do plants grow faster when people sing to
them?" This question is valid because it is testable, and it does not ask about emotions.
14. A question for a scientific investigation needs to be testable; it also needs to be connected to
science concepts.
The question about the number of planets in a galaxy is connected to science, but it is not
testable because he is unable to travel to the nearest galaxy, nor can he detect the planets from
Earth.
15. Darren hypothesized that the volume of a gas is related to its temperature. The observation
from which he based his hypothesis was that a balloon filled with air expanded when it was
heated and shrank when it was cooled. This observation shows a direct relationship between
the volume of a gas and its temperature.
It is always important for an investigator to be able to identify observations which support a
hypothesis or prediction. Equally, it important to acknowledge any observations which do not
support a hypothesis or prediction.
16. All testable hypotheses are valuable because their corresponding scientific investigations
produce evidence, data, and information from which scientists can develop other theories, ideas,
and investigations.
It doesn't matter if a hypothesis is proven to be correct or incorrect as long as the hypothesis is
valid (i.e., clear, measureable, testable).
17. A hypothesis is a statement that can be tested. The best hypotheses are clear statements
that attribute an effect to a definite cause.
18. A scientific hypothesis must be testable and it must be written as a statement, not as a
question. "The birds follow the herd because the cows stir up insects for the birds to eat" is a
testable hypothesis.
19. All scientific investigations begin with an observation. A hypothesis is a tentative
explanation of an observation, or a statement that proposes a possible explanation to some
phenomenon or event.
Formulating a hypothesis involves asking a question about the observation. Hypotheses bring
observations together into generalizations from which predictions can be made.
20. A hypothesis is best described as an educated guess that attempts to explain a phenomenon
or predict the outcome of an experiment.
Hypotheses should be written as statements (e.g., Greyhounds run faster than other breeds of
dogs, or if salt is added to ice, then the freezing point will be lower). Hypotheses should not be
written as questions.
21. Hypotheses are not questions. Hypotheses are statements which can be tested for validity.
If the statement is not testable, it is not a good hypothesis.
22. Jobi was not correct about his experiment being a waste. Hypotheses are always valuable,
even when they turn out to be incorrect, because they lead to new information which can be used
in other hypotheses and investigations.
23. Most scientific theories start as hypotheses. After many repeated experiments and
different lines of evidence all indicate that a hypothesis is correct, the hypothesis may be
adopted by the scientific community as a theory.
24. Since the idea of the big bang is supported by scientific evidence, it is called a theory.
It is not called a fact because it has not been proven.
25. In science, a theory is a unifying explanation for a broad range of hypotheses and
observations that have been supported by testing. The gathering of evidence and the peer review
of that evidence are hallmarks of scientific thought.
26. Many times people will use the word theory when they are really just stating an opinion or
speculating. These opinions and speculations cannot be proven right or wrong.
A scientific theory, on the other hand, is a well-supported explanation of nature. It is based on
scientific knowledge and has been tested through experimentation.
In this case, the best time to wash a car is really a matter of opinion and not a testable
explanation of nature.
27. The idea that the Sun is at the center of the solar system was not originally accepted, despite
convincing evidence, because it is difficult to change a commonly held belief. Science changes
constantly, as new inventions and methods are created to achieve more reliable data. It is
important that people understand that science changes and that even commonly believed theories
can change as new information is presented.
28. Scientific knowledge is open to change as new information is learned.
Perhaps the biggest reason why scientific information has proved to be so useful and lasting is
that it is constantly subject to change. Theories and explanations only last as long as they're able
to accurately predict what will happen in experiments. So when significant data is gathered that
contradicts a theory, that theory must be modified to agree with the data. Sometimes this means
the theory needs to be abandoned completely.
29. New scientific knowledge is often used to reevaluate existing theories.
Some scientific theories are very good at describing the way the world works. But even very
good theories sometimes come up against new information that does not agree with them. When
this happens, the theory needs to be reevaluated.
The result is usually that the theory is refined and made more accurate, taking into account the
new information.
30. Germ theory, which predicts that life and diseases can arise from living things too small to
see, has existed for thousands of years, but it was generally not believed. Louis Pasteur's
experiment provided a scientific observation that went against the theory of spontaneous
generation, thus disproving that theory and paving the way for germ theory to gain popularity.
31. In an experiment, the independent variable controls the dependent variables.
For example, if a student wants to determine how the amount of water a plant is given affects the
growth of a plant, the independent variable (the amount of water) controls the dependent variable
(the growth of the plant).
32. The dependent variable is the one that is measured to see what effect changing the
independent variable has on it. In this experiment, the independent variable is the amount of
caffeine. The dependent variable measures how the caffeine changes the reaction time for each
person.
33. The observed results of an experiment that occur from changes in the independent variable
are known as dependent variables. For example, if a student wants to determine how the
amount of water given to a plant effects how much the plant grows, the growth of the plant is the
observed result that occurs because of changes to the amount of water the plant receives.
34. In a controlled scientific experiment, a scientist alters one variable, called the independent
variable. The scientist then studies the effects of this alteration on another variable, called the
dependent variable. Any other variables involved the experiment are kept constant.
35. Variables are the parts in an experiment which change. Independent variables determine the
values of the dependent variables.
In Omar's experiment, the independent variable is the mass of the model rocket. This variable
is controlled by Omar and ultimately determines the values of the dependent variable (the
amount of time that the rockets remain airborne).
36. Lexi is trying to decide whether the crime rate depends upon the county population. The
crime rate is the dependent variable.
37. A dependent variable is a variable in an experiment that is passively observed. The
dependent variable is affected by the independent variable.
38. In this experiment, the independent variable is the material each pan is made of. The
dependent variable is how long it takes each ice cube to melt. All other variables should be kept
constant, including the amount of ice put in each pan, the temperature of each pan, and the
temperature of each ice cube.
39. Since Jose changed more than one variable at a time, he cannot make statements like "the
box traveled farther on linoleum than on carpet," "more massive boxes did not travel as far," or
"greater spring compression caused the box to travel farther." He did not learn anything
conclusive or meaningful about how each variable affected the results because he changed more
than one at a time.
40. In this experiment, Sarah wants to know where to plant the chamomile. Since she waters the
garden by hand, the amount of water given to the chamomile will not be affected by where the
plants are. The amount of sunlight the chamomile gets will depend on where it is planted: under
the trees, near them, or far from them. To find out how much sunlight they need, Sarah should
keep the type of chamomile plants she uses, the type of soil she uses, and how much water she
gives the plants the same. She should change how much sunlight the chamomile gets and
measure the height of the plants over time. That will tell her which plants grow the best.
41. Variables are factors that can be changed during an experiment.
The constants of an experiment are the factors that are kept the same throughout different trials
of the experiment.
42. A good control for this experiment would be to slide each block down its ramp with no
liquid on it first, then add the liquid and slide the block down it again.
43. When designing an experiment for a controlled scientific investigation, the designer should:





plan the variables (manipulated and responding)
plan for controlled variables
list the needed materials
list the procedures
plan for recording, organizing and analyzing data from the experiment
44. Many variables can affect an experiment.
Jack's experiment could be affected by anything that might affect the growth rate of the bacteria
that Jack is studying. For example, the bacteria's growth could be affected by the light level, the
type of nutrients provided, the bacteria's species, the temperature, and so on.
Variables that are separated from the bacteria's growth environment, such as the clothes Jack is
wearing, will not affect the experiment.
45. There are several ways to make sure the results of an investigation are valid. First, you and
others can try to repeat the experiment. In addition, if it is a controlled experiment, you can make
sure you have a control, only one independent variable, at least one dependent variable, and
constants.
In this case, Julia has multiple independent variables (the color of the fabric and the light
source), so the results will not be valid.
46. There are several ways to make sure the results of an investigation are valid. First, you and
others can try to repeat the experiment. In addition, if it is a controlled experiment, you can make
sure you have a control, only one independent variable, at least one dependent variable, and
constants.
For Ned's results to be valid, he needs to test the hand sanitizers on bacterial colonies that are
kept in the exact same environmental conditions, such as temperature and light level.
47. Scientific experiments must have a control group to be used for comparison. The control
group is exposed to the same conditions, without being exposed to the independent variable. In
this case, Beth should have placed several identical ice cubes in the windowsill without any salt.
This would show how quickly the ice would melt without salt. Someone reading the data could
then make a conclusion based on the results. The melting times of the two groups of ice cubes
could be compared to determine whether or not salt affected how fast ice melts.
48. For an experiment to be reliable, there can be only one independent variable. In this scenario,
there were two. The first was whether or not the plants were given plant food. The second was
the type of seed. For the test to be reliable, he should have used the same kind of seed for each
plant. Then, some should have been given plant food while the rest were not. If someone else
were to repeat the experiment, they would need to know what types of seeds were used. And,
they would need to have only one independent variable in order to get reliable results.
49. Javier must carefully record and describe all of the characteristics of his beetle.
Javier might have found a new species of beetle. But he will only be able to figure this out if he
has carefully recorded all of the details of the beetle. So Javier must closely observe it, and take
careful notes. After he has done this, he can compare his description to that of known species.
50. In order to see if the mass of the water changed, Selma first needs to find out what the mass
of the liquid water is in order to compare it to the mass of the frozen water.
51. To test his hypothesis, Nick should heat equal masses of wax and chocolate and measure
their temperatures when they start to melt.
52. To find the answer to a question about nature, it is best to plan an experiment in which the
natural event in question can be directly observed and measured.
53. When you are planning an experiment write down what types of data you need in order to
answer your question. In this case, Gabriel needs to know the temperature of the wax when it
starts to melt. To determine this, he should measure the temperature of melting wax.
54. Kyle must change the force applied to the ball. Since he wants to see how the ball's motion
is affected by its initial speed, Kyle should keep every factor in his investigation the same
throughout his trials except for the ball's initial speed. To change the ball's initial speed, he must
apply a different force each time he throws it.
55. The scientist should design an experiment with three groups of plants—a group fertilized by
X, a group fertilized by Y, and a control group with no fertilizer. All three groups should receive
the exact same treatment in the experiment, except for how they are fertilized. This will allow the
scientist to study the effects of the different fertilizers on the plants.
56. The best way to see how weather affects cell phone reception is to observe the reception of a
single cell phone in the same location under various atmospheric conditions. You should not
move the cell phone to a different location because that would add the variable of the cell
phone's position in relation to a reception tower.
57. The best way to see how weather affects cell phone reception is to observe the reception of a
single cell phone in the same location under various atmospheric conditions. You should not
move the cell phone to a different location because that would add the variable of the cell
phone's position in relation to a reception tower.
58. During an experiment to test how a variable changes a substance, it is important to first
observe and record the characteristics of the substance before the variable is introduced. In this
case, the variable is heat energy. The student must first record the liquid’s volume, before
attempting to change the volume by introducing heat energy.
59. In a controlled experiment, only one factor (the independent variable) should vary. David
currently has two independent variables in his experiment (a watering schedule for one tree and a
fertilizer treatment for the other tree). David can improve his investigation by testing only one
independent variable at a time.
60. The ice lowers the temperature of the solution, which decreases the amount of salt that can be
dissolved in it. However, as the ice melts, it also adds water to the solution, which increases the
amount of salt that can be dissolved in it. The net results of adding ice to the solution will be
unpredictable because the ice changes two variables at the same time.