Know how and how much to tip people who expect gratuities, even in the case of poor service.

Geometry is beautifully logical, and it teaches you how to think and prove that things are so, step by step by step. Proofs are excellent lessons in reasoning. Without logic and reasoning, you are dependent on jumping to conclusions or - worse - having empty opinions.

No one would choose to be jerked randomly off task again and again until you have half a dozen things you're trying to get done, all at the same time.

Know the difference between principles based on right or wrong vs. principles based on personal gain, and consider the basis of your own principles.

I think change is possible, but only for individuals who were never truly gay in the first place and who have a strong personal motivation to recover their heterosexuality.

Know the official post office abbreviations for all 50 states without having to consult a list.

Know how to drive safely when it's raining or when it's snowing. The two conditions are different.