Appropriate age:
Preschool and Younger

Description of technique:
It sounds unnecessary, but young children often need just the smallest bit of insurance against embarrassing accidents at school. Kids are routinely taken to the bathroom several times daily after they arrive, but teachers tell me that many kids have accidents within moments of arrival (or sometimes on the bus, if that applies). You just have to build in that last visit to the pot as prerequisite to signing in or to leaving for the bus.

Other comments or suggestions:
Children can be unbelievably ornery in the things they say to each other on this subject, even at an early age, so it's worth a bazillion points to your child's self-esteem to help out in this little way.