[Music] what are variables in science variables are all the things that can vary or change in an experiment To see how variables work let's set up an imaginary experiment testing the effect of vitamins on squid lifespan Here are two groups of squid One will receive vitamins and the other will not In this experiment and every other experiment there are three types of variables one the independent variable This is the variable that you manipulate the thing that you are investigating So in an experiment testing how vitamins affect squid lifespan the amount of vitamins given to your squid is the independent variable As the experimentter you decide to change this variable It does not depend on any other variables in the experiment which is why it is called the independent variable Good experiments only have one independent variable Two the dependent variable This is the variable that you are measuring Think of this as your results In our experiment the dependent variable would be squid lifespan because lifespan depends on what you change in your experiment Three controlled variables These variables are all the things that you keep constant in your experiment So in our squid experiment you would need to have many controlled variables In fact any variable that could affect your results besides your independent variable should be controlled Temperature food type and water quality are all examples of controlled variables in this experiment and should be kept the same for both groups of squid Controlled variables are super important If you fail to control your variables your experimental results will be meaningless Let's see why Imagine that you don't control these variables The control group squid are kept in a tank with a temperature of 20° C and are given normal squid food and clean water but no vitamins But our experimental group is kept in a tank with a temperature of 90° C and fed nacho cheese while swimming in dirty water We also give them vitamins Now let's say all our experimental group is squid die after 2 hours Does this mean that vitamins kill squid there is no way to know the effect of vitamins because we did not control our controlled variables The squid could have died from being nearly boiled or from nacho cheese or from the dirty water Because we did not control these variables we cannot answer our question about the effect of vitamins on squid On the other hand if we control our variables and make sure both groups get the same temperature the same food and the same water quality and only change the amount of vitamins our independent variable we'll be able to answer our question So remember in an experiment only change one variable your independent variable Make sure you keep all other variables controlled and then you will be able to measure your dependent variable or results If you enjoyed this video please like it subscribe and check out the other free games quizzes and interactive learning experiences at Biomman Biology [Music]