1. Potential energy is stored energy.

2. Three Types of Potential Energy
Elastic
Gravitational
Chemical
** There are other types, but these are the three that you need to know for 6th grade.

3. Elastic Potential Energy
Elastic potential energy is energy stored as a result of applying a force to deform an elastic object.
The energy is stored until the force is removed and the object springs back to its original shape, doing work in the process.
The deformation could involve compressing, stretching or twisting the object.

4. Elastic Examples
Many objects are designed specifically to store elastic potential energy, for example:
The coil spring of a wind-up clock
An archer's stretched bow
A bent diving board, just before a divers jump
The twisted rubber band which powers a toy airplane
A bouncy ball, compressed at the moment it bounces off a brick wall.

5. Gravitational Potential Energy
It represents the potential an object has to do work as a result of being located at a particular position in a gravitational field.
The energy is stored as the result of the gravitational attraction of the Earth for the object. 

6. Gravitational Examples
Gravitational potential energy is the energy stored in an object as the result of its vertical position or height.
For example, a pen being held above a table has a higher gravitational potential than a pen sitting on the table. 

7. Chemical Potential Energy
Energy that can be absorbed or released during a chemical reaction or phase transition
Chemical potential energy is the energy stored in the chemical bonds of a substance.

8. Chemical Examples
The various chemicals that make up gasoline contain a large amount of chemical potential energy that is released when the gasoline is burned in a controlled way in the engine of the car. 
Dynamite is another example of chemical potential energy.
Food - The chemical energy in food is released while the food is being digested and the molecules of food are broken down into smaller pieces.
Dry wood stores chemical energy. 
Batteries - You cannot see the energy in the battery when the battery is just sitting around; it is when the electricity is produced that the energy is seen.