99.+What+is+a+Fair+Test?

** A Fair Test **
A 'fair test' is one in which you only change one thing (i.e. one variable). This called the independent variable. All other variables must be kept the same.

Your experiment results will often show something (i.e. another variable) changing. This is called a dependent variable. (It's value depends on the thing you change)

e.g. Which cup of tea is the sweetest after adding 1 teaspoon of sugar?


 * [[image:http://polandian.home.pl/wp-content/uploads/2009/11/cup-of-tea.jpg width="229" height="177"]] || [[image:http://www.rukakuusamo.com/notesfromlapland/wp-content/uploads/2010/08/cupOfTea.jpg width="175" height="175"]] ||

If they have the same amount of sugar, surely this means they will have the same sweetness. Or does it? This is only true if the amount (volume) of tea is the same in each cup. To be really sure you will also need to make sure the tea is of the same type and kept at the same temperature too.