Experimental Design Unit 1.02

Which statement best describes an independent variable?

• The variable that responds to change in an investigation.
• The variable you change in an investigation
• The effect in a cause-effect relationship.
• The factor that can never change in an investigation.

Which of the following best describes the dependent variable?

• The variable that responds to change
• The variable that is deliberately changed
• The variable kept constant
• The treatment in an investigation

Liam did an investigation to see how water temperature affects the amount of salt that will dissolve in the water. He filled 4 beakers with exactly 100 milliliters of water each. He then heated each beaker to a different temperature and tested salt solubility at each different temperature. What was Liam's independent variable?
Hint: What did you change?

• Amount of water in each beaker.
• The number of beakers
• The amount of salt that dissolved in each beaker
• The temperature of the water in each beaker

Trout are a type of fish that live in freshwater ponds and streams. Raychelle did an investigation to see how the amount of nitrogen in pond water affects the number of trout in the water. She tested the water of 20 different ponds in her city. Each one had a different amount of nitrogen in it. She then did a study to determine the number of trout in each pond. She compared the amount of nitrogen to the number of trout in each pond. What was Raychelle's dependent variable?
Hint: What is the change you are looking for?

• The number of trout in each pound
• The number of ponds in her study
• The amount of nitrogen in each pond
• The type of fish she studied (trout)

Which of the following describes the treatment in an investigation?

• A controlled test designed to answer a question or solve a problem
• The factor that responds to a change
• The factor that is kept constant
• The factor that is changed in order to observe a response

A student conducts an experiment to determine how the addition of salt to water affects the density of the water. The student fills 3 beakers with equal amounts of water. He then adds 1 cup of salt to the first beaker, 2 cups of salt to the second beaker and no salt to the third beaker. What is the dependent variable in the student's investigation?

• The amount of salt in the water
• The temperature of the water
• The density of the water
• The ph of the water

What two traits must a viable hypothesis have?

• Testable and true
• Measurable and factual
• Testable and falsifiable (ability to be tested)
• Be in the form of question and be based on previous work

Jose writes the following hypothesis: If a rose bush receives nitrogen rich fertilizer then it will produce more roses than a rose bush that does not receive nitrogen rich fertilizer. Which of the following is a true statement about Jose's hypothesis?

• Jose's hypothesis is neither testable nor falsifiable 
• Jose's hypothesis is both testable and falsifiable
• Jose's hypothesis is testable but not falsifiable
• Jose's hypothesis is not testable but is falsifiable

A variable answered by a simple "yes" or "no" is not measureable.

• True
• False

A variable can be measured using numbers and units and can also be answered by making observations that result in simple "yes" or "no" answers.

• True
• False