Scientific Method Variable Practice

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Scientific Method Variable Practice
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Terms to remember

• Control group- A part of the experiment that is
  not being tested and is used for comparison (the
  normal).
• Variable - Any part of an experiment that can
  vary.
• Independent Variable - The part of the experiment
  that is manipulated or changed by the scientists
  or person performing the experiment.
• Dependent Variable - The part of the experiment
  that is affected by the independent variable.
• Controlled Variable- Variables that are kept
  constant (or the normal)

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Given the information in the experiment,
determine the answers to the questions.
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Fly AwayStudents at DHS wanted to test if paper
weight affects the distance paper airplanes fly.
The same type of paper airplanes were folded from
three different weight papers. The planes were
thrown in the mall area to measure the distance
they would fly. What are the following variables?

• 1. Independent variable? ___________________
• 2. Dependent variable? _____________________
• 3. Controlled variables? ____________________

Weight of paper
Distance the plane flew
Type of paper, area where the plane was thrown,
same folding, .
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LemonadeA group of students was asked to compare
the taste of lemonade. One glass was from a
pitcher made with one cup of sugar. The second
glass was made from a pitcher with two cups of
sugar. Both pitchers used the same amount of
water, lemon juice, and ice. What are the
following variables?
Amount of sugar

• 1. Independent variable? ___________________
• 2. Dependent variable? _____________________
• 3. Controlled variables? ____________________

Taste
Ice, amount of water, lemon juice, ..
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Follow the lightStudents in a science class did
an experiment in which they pointed a flashlight
at a screen. They put the flashlight at a
different distance from the screen. They
measured the diameter of the lighted spot. What
are the variables?
Flashlight distance

• 1. Independent variable? ___________________
• 2. Dependent variable? _____________________
• 3. Controlled variables? ____________________

Diameter of light
Same flashlight, ..
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Water DensityA student wanted to find if
temperature had an effect on the density of
liquid water. She measured the density of 50 cm3
of water at 0C, 20C, 40C, 60C , 80C, and
100C. What are the variables?
Temperature

• 1. Independent variable? ___________________
• 2. Dependent variable? _____________________
• 3. Controlled variables? ____________________

Density
Type of water, container the water is in, type of
thermometer, ..
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Krusty Krabs Breath MintsMr. Krabs created a
secret ingredient for a breath mint that he
thinks will cure the bad breath people get from
eating crabby patties at the Krusty Krab. He
asked 100 customers with a history of bad breath
to try his new breath mint. He had fifty
customers (Group A) eat a breath mint after they
finished eating a crabby patty. The other fifty
(Group B) also received a breath mint after they
finished the sandwich, however, it was just a
regular breath mint and did not have the secret
ingredient. Both groups were told that they were
getting the breath mint that would cure their bad
breath. Two hours after eating the crabby
patties, thirty customers in Group A and ten
customers in Group B reported having better
breath than they normally had after eating crabby
patties.
Group B

• 1. Which people are in the control group?
  __________________
• 2. What is the independent variable?
  _______________________
• 3. What is the dependent variable?
  ________________________

Secret ingredient in the breath mint
Amount of breath odor (or bad breath)
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SpongeBob Clean PantsSpongeBob noticed that his
favorite pants were not as clean as they used to
be. His friend Sandy told him thathe should try
using Clean-O detergent, a new laundry soap she
found at Sail-Mart. SpongeBob made sure towash
one pair of pants in plain water and another pair
in water with the Clean-O detergent. After
washing bothpairs of pants a total of three
times, the pants washed in the Clean-O detergent
did not appear to be any cleanerthan the pants
washed in plain water.
Laundry soap

• 1. What is the independent variable?
  _______________________
• 2. What is the dependent variable?
  ________________________
• 3. What should Sponge Bobs conclusion be?

Amount of dirt left on the pants (how clean the
pants were)
Clean-O laundry soap does not appear to be
effective in cleaning his pants.
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Squidwards SymphonySquidward loves playing his
clarinet and believes it attracts more jellyfish
than any other instrument he has played. In order
to test his hypothesis, Squidward played a song
on 3 instruments for a total of 5 minutes and
counted the number of jellyfish he saw in his
front yard. He also recorded the number of
jellyfish he observed when he was not playing an
instrument.
3 trials with no music

• 1. What is the control group? ____________________
  _________
• 2. What is the independent variable?
  _______________________
• 3. What is the dependent variable?
  ________________________

Instrument
Number of jellyfish
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Super BubblesPatrick found some Super Bubble
Soap at Sail-Mart. The ads claim that Super
Bubble Soap will produce bubbles that are twice
as big as bubbles made with regular bubble soap.
Patrick and SpongeBob made up two samples of
bubble solution. One sample was made with 5 oz.
of Super Bubble Soap and 5 oz. of water, while
the other was made with the same amount of water
and 5 oz. of regular bubble soap. Patrick and
SpongeBob used their favorite bubble wands to
blow 10 different bubbles and did their best to
measure the diameter of each one. What are the
variables?
Type of bubble solution

• 1. Independent variable? ___________________
• 2. Dependent variable? _____________________
• 3. Are the results reliable? Why or why not?

Size (diameter) of the bubble
The description does not say who blew the bubbles
for each solution. There may be differences in
bubble sizes due to the person blowing the bubble
rather than the bubble solution. They might have
considered having each person blow 5 bubbles with
each solution.