Independent / Dependent Variables
First let's look at the definitions and a sample.
Independent Variable
You have the power
You have control over the independent variable. You can manipulate it and intentionally change its value or worth. The Independent Variable is adjusted to observe what relationship it has with another quantity.
Dependent Variable
Measuring change
A dependent variable is the variable being measured in an experiment. The dependent variable is thought to "depend" on the independent variable. When you make changes to an independent variable you measure the effects on the dependent variable.
Sample
A group of researchers want to test how sunlight affects plant growth. The researchers have three plants, one that is given no sunlight, one that is given 4 hours of sunlight, and one that is given 8 hours of sunlight for ten consecutive days. After 10 days, the researchers measure the plants growth in centimetres.