Variables in Science

Master science variables! Learn to identify independent, dependent, and controlled variables in experiments.

Types of Variables Video Scientists use controlled experiments to figure out how the natural world works. A controlled experiment is a test where a scientist only changes one variable at a time. There are three types of variables. Click the link above to watch the video or read about the three variables below.Independent Variable:The one variable that is changed by the scientist. What the scientist is testing.Dependent Variable:The variable that changes in response to the independent variable. The data being collected in the experiment.Constant (Control) Variables:Variables that the scientist needs to keep the same throughout the experiments because they could cause a change if it is not controlled.Directions: Read the following questions and experiments, then identify the variables. Experiment 1Participants are divided into groups by age. An item is dropped and the time (reaction time) it takes the participant to catch the item is recorded. Word Bank: Reaction time, Age, Item dropped Question Independent Variable Dependent Variable Controlled Variable (Constant) How does age affect reaction time? Age Reaction time Item dropped Experiment 2A large dog and a small dog were given food in an automatic feeder. The amount of food each dog ate was recorded daily. Both dogs were given the same brand of dog food. Word Bank: Brand of dog food, How much food it eats, Size of the dog Question Independent Variable Dependent Variable Constant Variable How does the size of a dog affect how much food it eats? Size of the dog How much food it eats Brand of dog food Experiment 3Students in Mrs. Johnson's science class took their tests in a cold room while the students in Mrs. Farnsley's science class tested in a hot room. The student's performance was recorded. Word bank: Temperature, Subject, Student performance Question Independent Variable Dependent Variable Constant Variable Does the temperature of a classroom affect student performance? Temperature Student performance Subject Experiment 4 Word bank: Distance ran, Heart rate, Time of day running Question Independent Variable Dependent Variable Constant Variable Does running in the morning increase my heart rate more than running in the evening? Time of day running Heart rate Distance ran Experiment 5 Word Bank: Productivity of worker, Satisfaction of worker, Type of job Question Independent Variable Dependent Variable Constant Variable Does worker satisfaction increase productivity? Satisfaction of worker Productivity of worker Type of job Write a proper hypothesis for any of the above testable questions. Be sure to begin with "If" and then have the IV followed by "then" with the DV!Make a specific PREDICTION. Identify whether the data is quantitative or qualitative. Quantitative height of plants diameter of a bubble time to run a mile Qualitative color of the liquid frog's behavior in cold environment texture of cotton ball