To have a good knowledge of that thing.
To challenge you knowledge in front of your audience.
To observe the effects of what you explained.
Experimenting is the best argument for a statement.
Tu understand very well that subject.
To give a benefit to your audience.
To show something about your inner self.
Simplification is the ultimate sophistication.
To learn naturally.
To show self-confidence.
To express creatively your personality.
Playing is the most intense learning.