# Identifying Variables & Experimental Design (Practice)

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## Transcript Of Identifying Variables & Experimental Design (Practice)

Per. #______

Date: ______________

Name(s):

Identifying Variables & Experimental Design (Practice)

BENCHMARKS: IOD 302: Understand basic scientific terminology; IOD 303: Find Brief Information in a body of text;

SIN 301: Understand the methods and tools used in a simple experiment; SIN 403 – Identify a control in an experiment

CCSS: RST 11-12.8; WHST.9-10.9 Time Allotted: 45 minutes (10 questions)

For the following, a brief description of an experiment is given; define/identify the (I.V.) independent variable, (D.V.) dependent variable, (S.V.) standardizing variables – also known as constants, (C.G.) control group and (E.G.) experimental group. Extra Credit: Pick one experiment from the list, formulate a hypothesis (if…… then……) and design/create an empty data table to test your proposed hypothesis.

1. You water three sunflower plants with salt

I.V.

D.V.

water. Each plant receives a different

concentration of salt solution. A fourth plant

receives regular water. After a two-week period, the height of the plants is measured.

S.V. or Constants:

All other environmental conditions like amount

of sunlight, air quality, temperature, type of

soil, etc. were kept the same for all the plants. C.G.

E.G.

2. One tank of gold fish is fed the normal amount I.V.

D.V.

of food once a day. A second tank is fed twice a

day. A third tank is fed four times a day during a six week study. The fish’s weight is recorded

S.V. or Constants:

daily. All tanks were of the same size and

C.G.

E.G.

shape.

3. You want to test which size of soccer ball is

I.V.

D.V.

easiest to juggle with your feet. You test a size

3, size 4 and size 5 ball of the same brand. You count the seconds the ball stays in the air for

S.V. or Constants:

each of the trials. You allow yourself to use

the ball. Size 4 is the most common size for

C.G.

E.G.

soccer leagues.

4. In a laboratory experiment, the temperature of I.V.

D.V.

air in balloons is varied and the volume of the

balloons is measured. Balloons of three different sizes are tested; small, regular, and

S.V. or Constants:

large. All balloons in the experiment were

initially filled to the same air pressure.

C.G.

E.G.

5. The reaction distance (distance traveled by a I.V.

D.V.

car from spotting an obstacle to stepping on

the brakes) for different types of drivers is being tested. Distracted drivers like DUI

S.V. or Constants:

(driving under influence), substance abuse,

talking on a cellphone, texting and driving, etc.

are compared to safe drivers under similar

C.G.

E.G.

conditions.

6. Stopping distance (distance traveled by a car I.V.

D.V.

after brakes are applied) for various highway

speeds is being tested for the new Chevy Volt. Defensive driving requires drivers to obey the

S.V. or Constants:

2 second rule to avoid rear end collisions.

However, many aggressive drivers ignore this

rule under normal driving conditions.

C.G.

E.G.

7. Schurz High School is testing the effect of a

I.V.

D.V.

new book bag policy on tardy to classroom.

Selected classes like English, Math, Social Studies would allow book bags and others

S.V. or Constants:

would restrict them. Data on the number of

students tardy to classes will be collected in

both groups and analyzed. Traditionally, book C.G.

E.G.

bags were not allowed into classrooms.

8. The effect of a cars speed on the gas mileage I.V.

D.V.

was tested for a new car. The car was driven at

different constant speeds ranging from 20 mph

to 100 mph on the same highway and the

S.V. or Constants:

mileage was recorded. The factory rated

highway mileage for the car is 34 mpg at a

C.G.

E.G.

speed of 40 mph.

9. Galileo rolled spherical objects down inclined I.V.

D.V.

planes with and without friction. He measured

time for different angles of inclination. Under S.V. or Constants:

normal conditions there is rolling friction

between the inclined surface and the rolling

object.

C.G.

E.G.

10. A scientist conducts an experiment to test the I.V.

D.V.

theory that vitamins could extend a person’s

life-expectancy. She collects data from various

doctors who had served senior citizens for the past decade. Her focus group included senior

S.V. or Constants:

citizens alive and deceased from that age

group and both vitamin and non-vitamin users. C.G.

E.G.

Per. #______

Date: ______________

Name(s):

Identifying Variables & Experimental Design (Practice) KEY

BENCHMARKS: IOD 302: Understand basic scientific terminology; IOD 303: Find Brief Information in a body of text;

SIN 301: Understand the methods and tools used in a simple experiment; SIN 403 – Identify a control in an experiment

CCSS: RST 11-12.8; WHST.9-10.9

For the following, a brief description of an experiment is given; define/identify the (I.V.) independent variable, (D.V.) dependent variable, (S.V.) standardizing variables – also known as constants, (C.G.) control group and (E.G.) experimental group. Extra Credit: Pick one experiment from the list, formulate a hypothesis (if…… then……) and design/create an empty data table to test your proposed hypothesis.

1. You water three sunflower plants with salt

I.V. Different

D.V. Height of the

water. Each plant receives a different concentration of salt solution. A fourth plant

concentration of salt.

plants.

receives regular water. After a two-week

S.V. or Constants: Same plant, two week period,

period, the height of the plants is measured. same environmental conditions.

All other environmental conditions like amount

of sunlight, air quality, temperature, type of C.G. Fourth plant fed E.G. The three plants

soil, etc. were kept the same for all the plants. with regular water.

fed with salt water.

2. One tank of gold fish is fed the normal amount I.V. Normal amount of D.V. Fish’s weight.

of food once a day. A second tank is fed twice a food once a day.
day. A third tank is fed four times a day during

a six week study. The fish’s weight is recorded S.V. or Constants: Same type of fish (goldfish),

daily. All tanks were of the same size and shape.

same tanks, and same time duration.

C.G. The fish fed with E.G. Fish in tanks fed

normal food.

with more food.

3. You want to test which size of soccer ball is easiest to juggle with your feet. You test a size 3, size 4 and size 5 ball of the same brand. You count the seconds the ball stays in the air for each of the trials. You allow yourself to use both of your feet, knees, and head to juggle the ball. Size 4 is the most common size for soccer leagues.

I.V. Different sizes of soccer ball.

D.V. Time in seconds.

S.V. or Constants: Same brand, juggling the ball in the same manner.

C.G. Size 4 ball.

E.G. Balls of size 3 & 5.

4. In a laboratory experiment, the temperature of I.V. The temperature D.V. Volume of the

air in balloons is varied and the volume of the balloons is measured. Balloons of three

of air in the balloons.

balloons.

different sizes are tested; small, regular, and S.V. or Constants: Same air pressure.

large. All balloons in the experiment were

initially filled to the same air pressure.

C.G. Regular size

E.G. Small and large

balloons.

size balloons.

5. The reaction distance (distance traveled by a car from spotting an obstacle to stepping on the brakes) for different types of drivers is being tested. Distracted drivers like DUI (driving under influence), substance abuse, talking on a cellphone, texting and driving, etc. are compared to safe drivers under similar conditions.

I.V. Different types of drivers.

D.V. Reaction distance.

S.V. or Constants: Same car and similar driving conditions.

C.G. Safe drivers.

E.G. Distracted drivers.

6. Stopping distance (distance traveled by a car after brakes are applied) for various highway speeds is being tested for the new Chevy Volt. Defensive driving requires drivers to obey the 2 second rule to avoid rear end collisions. However, many aggressive drivers ignore this rule under normal driving conditions.

I.V. Different speeds. D.V. Stopping distance.
S.V. or Constants: Same car (Chevy Volt).
C.G. Defensive drivers E.G. Aggressive who obey the 2 sec. rule drivers.

7. Schurz High School is testing the effect of a new book bag policy on tardy to classroom. Selected classes like English, Math, Social Studies would allow book bags and others would restrict them. Data on the number of students tardy to classes will be collected in both groups and analyzed. Traditionally, book bags were not allowed into classrooms.

I.V. The new book bag policy.

D.V. Tardy to classrooms.

S.V. or Constants: Same students, same school, same passing time, and same discipline policy.

C.G. Classes still restricting book bags.

E.G. Classes allowing book bags.

8. The effect of a cars speed on the gas mileage I.V. Different car

D.V. Gas mileage.

was tested for a new car. The car was driven at speeds.
different constant speeds ranging from 20 mph

to 100 mph on the same highway and the

S.V. or Constants: Same car.

mileage was recorded. The factory rated

highway mileage for the car is 34 mpg at a speed of 40 mph.

C.G. Factory rated mpg E.G. Other mpg’s.

9. Galileo rolled spherical objects down inclined planes with and without friction. He measured time for different angles of inclination. Under normal conditions there is rolling friction between the inclined surface and the rolling object.

I.V. Angle of inclination D.V. Time

S.V. or Constants: Spherical objects, gravity.

C.G. Time with rolling friction.

E.G. Time with less or no rolling friction.

10. A scientist conducts an experiment to test the theory that vitamins could extend a person’s life-expectancy. She collects data from various doctors who had served senior citizens for the past decade. Her focus group included senior citizens alive and deceased from that age group and both vitamin and non-vitamin users.

I.V. Vitamin usage.

D.V. Life-expectancy.

S.V. or Constants: Same age group, same doctors.

C.G. Non-vitamin users E.G. Vitamin users.
ConstantsDriversBalloonsExperimentConditions