Originally Posted by Cat Herder:
"Parents are expected to give a minimum of 2 weeks written notice (14 business days) of termination of contract."
The simpler it is worded the easier to enforce. 
Yes--I agree about simpler is better. My policy is worded something like your example. Unfortunately, it doesn't stop them from giving notice 2 weeks before my vacation, and therefore not paying for the vacation I've been working all year to earn. Saying no to that is something I can't figure out how to word simply. :-(