Model Leg, or officially Model Legislature is an activity run by schools in which they try to simulate the government of their state or nation.
It is quite like Model UN, but it has its differences. Instead of debating one single topic with many different resolutions on the table, only one bill is debated at a time, and the each day covers many different topics, from education to health care to economic reform.
My personal experiences with Model Leg have been quite fun, passing a bill banning social promotion in model leg law in the State of Rhode Island and Providence Plantations. Of course, it doesn't really become a state law, but it is entered into a really big book which is used for the laws in a simulated Rhode Island. Those laws are used when formulating new bills in the next years.