- Energy is something that makes a change. Making a change is called "doing work."
- Scientists define energy this way: Energy is the ability to do work.
- The total amount of energy in the universe always has been and always will be the same.

Energy comes in many different forms.
- Energy has many different forms. These are the most common:
- Solar energy
- Heat energy
- Light energy
- Radiant energy
- Chemical energy
- Mechanical energy
- Magnetic energy
- Electrical energy
- Nuclear energy
- Energy can be transferred, but it cannot be created or destroyed.
- When energy is used, it changes from one form of energy to another.
- Example: When coal is burned, its energy is changed into heat and light.
- When energy is used, it changes from one form of energy to another.