For the first 11 years of its existence, which governmental system did the united states use?
monarchy
confederation
federation
theocracy

For the first eleven years of its existence, the United States implemented a "B. Confederation" style government, since during this time most of the power was reserved by the individual states--not the central government. 

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.