What Is Evolution?
Evolution is the process by which different kinds of living organisms are believed to have developed from earlier forms during the history of the Earth.
How does evolution work?
Evolution works though a system called natural selection, Natural selection is when the environment chooses what animals survive.
How does Natural selection work?
Variations exists within all populations of organisms. This occurs because random mutations can be passed to an offspring. If a change in environment is more adaptable to a certain variation then they will reproduce more. Here is a short video that gives a good example. watch 3.23 to 9.00.