Classification of Variables

  1. Read the following investigations and find the variables.
  2. Classify the variables as control (list at least 3), independent (only 1), or dependent (only 1).

Investigation 1: Scientists were trying to determine if junk food would cause a mouse to gain weight. The diet of the mice varied. Some mice were given junk food. Others were given Mouse Chow. The mice were weighed daily. All mice were the same age and the same type mouse.

Kind of Variable / Answer
control
(list at least 3)
independent
(only ONE answer)
dependent
(only ONE answer)

Investigation #2: A scientist was trying to see if the amount of water a plant gets affects plant growth. He got ten identical plants and gave them different amounts of water. Their growth was measured daily. They received the same amount of sunlight.

Kind of Variable / Answer
control
(list at least 3)
independent
(only ONE answer)
dependent
(only ONE answer)

Investigation #3: A scientist was trying to determine if the shape of hot air balloons would affect how high it went. The shape of ten hot air balloons was varied. Some were oval and others round. The altitude (how high they went) was measured. The scientist tested them on the same day so the weather conditions would be the same. The balloons were the same size.

Kind of Variable / Answer
control
(list at least 3)
independent
(only ONE answer)
Dependent (only ONE answer)

Investigation #4: A gardener wants to know if music helps plants to grow. The gardener buys ten identical plants. Each plant gets the same amount of sunlight and water every day. Five of the plants hear classical music for one hour each day. The other five plants hear no music. The height of each plant is measured daily.

Kind of Variable / Answer
control
(list at least 3)
independent
(only ONE answer)
dependent
(only ONE answer)

Find the Variable

Read each experiment below. Study the data results. Decide what variable is being tested and write it on the blank lines.

  1. Three corn seedlings were placed in three test tubes. The test tubes were taped on a bulletin board as shown. Here are the test results after one week of growth.

Test Tube / Stem Grew / Root Grew
A / Up / Down
B / Up / Down
C / Up / Down
Kind of Variable / Answer
control
(list at least 3)
independent
(only ONE answer)
dependent
(only ONE answer)
  1. Ten pill bugs were placed at one end of a shoebox. The other end of the box was divided into two parts, one wet and the other dry. The air temperature was 22°C. The data below shows where the bugs were after five minutes.

Trials / Air Temperature / Wet / Dry
1 / 22°C / 8 / 2
2 / 22°C / 7 / 3
3 / 22°C / 9 / 1
Kind of Variable / Answer
control
(list at least 3)
independent
(only ONE answer)
dependent
(only ONE answer)
  1. Three foods were tested to see if they contained starch. Iodine solution is used to test for starch. Iodine turns from reddish/brown to a blue/black, if starch is present.

Foods Tested / Stem Grew / Root Grew
water / Reddish/brown / No
Bread / Blue/black / Yes
Egg white / Reddish/brown / No
Kind of Variable / Answer
control
(list at least 3)
independent
(only ONE answer)
dependent
(only ONE answer)