What is a variable? Basically, a variable is any factor that can be controlled, changed, or measured in an experiment. Scientific experiments have several types of variables. The independent and dependent variables are the ones usually plotted on a chart or graph, but there are other types of variables you may encounter. In a science experiment , only one variable is changed at a time the independent variable to test how this changes the dependent variable. The researcher may measure other factors that either remain constant or change during the course of the experiment but are not believed to affect its outcome.
These are controlled variables. Any other factors that might be changed if someone else conducted the experiment but seemed unimportant should also be noted. Also, any accidents that occur should be recorded. These are extraneous variables. In science, when a variable is studied, its attribute is recorded.
A variable is a characteristic, while an attribute is its state. For example, if eye color is the variable, its attribute might be green, brown, or blue. If height is the variable, its attribute might be 5 m, 2.
Actively scan device characteristics for identification. Use precise geolocation data. Project Guides.
View Site Map. Science Projects. Grade Levels. Physical Science. Earth and Environmental Science. Behavioral and Social Science. What are Variables? What is an Independent Variable? What is a Dependent Variable? What is a Control Variable? Teacher Tool Box. Water faucet opening closed, half open, fully open Amount of water flowing, measured in liters per minute The faucet Water pressure, or how much the water is "pushing" "Different water pressure might also cause different amounts of water to flow and different faucets may behave differently, so to ensure a fair test, I want to keep the water pressure and the faucet the same for each faucet opening that I test.
Temperature of the water measured in degrees Celsius Amount of sugar that dissolves completely, measured in grams Stirring Type of sugar "More stirring might also increase the amount of sugar that dissolves, and different sugars might dissolve in different amounts, so to ensure a fair test I want to keep these variables the same for each cup of water. Amount of fertilizer, measured in grams Growth of the plant, measured by its height Growth of the plant, measured by the number of leaves See Measuring Plant Growth for more ways to measure plant growth.
Same type of fertilizer Same pot size for each plant Same plant type in each pot Same type and amount of soil in each pot Same amount of water and light Make measurements of growth for each plant at the same time "The many variables above can each change how fast a plant grows, so to ensure a fair test of the fertilizer, each of them must be kept the same for every pot.
Voltage of the electricity, measured in volts Speed of rotation, measured in revolutions per minute RPMs Same motor for every test The motor should be doing the same work for each test turning the same wheel, propeller, or whatever "The work that a motor performs has a big impact on its speed, so to ensure a fair test, I must keep that variable the same.
Time measured, in minutes Height of candle, measured in centimeters, at regular intervals of time for example, every 5 minutes Use same type of candle for every test Wind—make sure there is none.
Groups receiving the survey: Teenagers or parents Amount of time that each person listens to music per day, measured in hours Ask the question in exactly the same way to each individual.
Teacher location: The teacher is either in the room or not in the room. Fenders: The bicycle either has fenders or it does not "Many engineering projects have alternative designs with independent variables like this one with and without fenders.
Riding at the same speed Same size and depth of puddle. Sample Here is a sample containing the variables and hypothesis. Explore Our Science Videos. Build a motion-activated guard robot. The faucet Water pressure, or how much the water is "pushing" "Different water pressure might also cause different amounts of water to flow and different faucets may behave differently, so to ensure a fair test, I want to keep the water pressure and the faucet the same for each faucet opening that I test.
One of the things to pay attention to in a science fair project is carefully maintaining all elements constant except for the experimental variables. Constants, also known as controlled variables, are elements that are carefully monitored to ensure that they stay the same across all the experimental groups.
Having constants in a science fair project helps to ensure that any differences between experimental groups are an effect of the independent variable that is being studied, not other factors. Constants must be identified before the experiment is begun. A good way to identify constants is to ask the question of what else might affect the dependent variable, which is the element being measured in the science fair project.
For example, in a science fair project that is measuring the effect of room temperature on the growth of broccoli seedlings, room temperature is the independent variable and height of seedling is the dependent variable. The constants include the type of pot, type and amount of soil, watering schedule and the depth at which seeds are planted.
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