Understanding Variables in Experiments

Which of the following could be an example of an independent variable in an experiment? (select all)

• The amount of sunlight a plant receives

• The height of the plant

• The type of soil used

• The temperature of the room

In an experiment to test the effect of different fertilizers on plant growth, what is the dependent variable?

• The type of fertilizer used

• The amount of water given to the plants

• The growth of the plants

• The type of plants used

Tags

DOK Level 1: Recall

Which of the following is a controlled variable in an experiment where you are testing the effect of temperature on the rate at which a substance dissolves?

• The temperature of the water

• The amount of substance used

• The solubility of the substance

• The type of substance used

Tags

DOK Level 1: Recall

Identify the independent variable in the following scenario: A scientist is testing the effect of different amounts of caffeine on the heart rate of mice.

• The heart rate of the mice

• The amount of caffeine given

• The type of mice used

• The environment in which the mice are kept

Tags

DOK Level 2: Skill/Concept

In an experiment to determine how the pH level of soil affects plant growth, what would be a controlled variable?

• The pH level of the soil

• The growth of the plants

• The type of plant used

• The amount of sunlight the plants receive

Tags

DOK Level 2: Skill/Concept

A researcher is studying the effect of different types of music on the concentration levels of students. What is the dependent variable in this study?

• The type of music played

• The concentration levels of students

• The duration of the study session

• The age of the students

Tags

DOK Level 2: Skill/Concept

In an experiment to test the effect of different amounts of water on plant growth, a student keeps the type of plant, the type of soil, and the amount of sunlight constant. What is the purpose of keeping these variables constant?

• To ensure that the experiment is fair and the results are reliable

• To make the experiment easier to conduct

• To increase the growth rate of the plants

• To reduce the cost of the experiment

Tags

DOK Level 3: Strategic Thinking

A scientist is investigating the effect of different temperatures on the rate of a chemical reaction. She keeps the concentration of reactants and the volume of the solution constant. What is the independent variable in this experiment?

• The rate of the chemical reaction

• The concentration of reactants

• The volume of the solution

• The temperature

Tags

DOK Level 3: Strategic Thinking

In an experiment to determine how the amount of sleep affects test scores, what would be a reasonable controlled variable?

• The amount of sleep

• The test scores

• The difficulty of the test

Tags

DOK Level 3: Strategic Thinking

A cow is given a growth hormone and then compared to another cow that was not given a growth hormone. Both cows were weighed at 2 years. What is the independent variable?

• The use of growth hormone

• The weight of the cows

• The age of the cows

• Time