Scientific MethodVocab Review to make life easier!

Variables

Variables used in an experiment or modeling can be divided into three types:

Independent Variable

Dependent Variable

Controlled

Independent Variable

The Independent Variable (IV) is something that causes a change in the experiment

Example: How much water flows through a faucet at different openings?

IV = Water faucet opening (closed, half open, fully open, etc.)

Example: Does heating a cup of water allow it to dissolve more sugar?

IV = Temperature of the water

Example: Does fertilizer make a plant grow bigger?IV = Amount of fertilizer

Dependent Variable

The Dependent Variable (DV) is the effect (or result) of the change in the experiment. This is what scientist measure in an experiment.

Example: How much water flows through a faucet at different openings?

DV = Amount of water flowing, measured in liters/min

Example: Does heating a cup of water allow it to dissolve more sugar?

DV = Amount of sugar that dissolves completely, measured in grams

Example: Does fertilizer make a plant grow bigger?DV = Growth of the plant, measured by its height

ControlledA Controlled Variable is something you try to keep constant (the same) in the experiment.

Example: How much water flows through a faucet at different openings?

C = The faucet; water pressure

Example: Does heating a cup of water allow it to dissolve more sugar?

C = Stirring; type of sugar

Example: Does fertilizer make a plant grow bigger?C = Same type of fertilizer; same size of pot for each plant; same type of plant in each pot; same type of soil for each plant; same amount of water and light…

Fair ExperimentsFor an experiment to be considered a fair test there should only be ONE independent variable

In other words, there should only be one cause for change/ one thing that could change the end result/effect

A fair experiment: Does the temperature of water affect how much sugar can be dissolved?

One cause = water temperature

An unfair experiment: Does the temperature of water and amount of sugar affect how much sugar can be dissolved?

Two causes = water temperature and sugar amount