Name at least four (4) differences between the terrestrial and jovian planets.

The terrestrial planets are closer to the sun, they are smaller that the jovian planets, they have less moons, and do not have a lot of gases on the surfaces. The jovian planets are farther away from the sun, they are much bigger than the terrestrial planets, have a lot of moons, at least two planets are gas giants, and at least two have rings, and they have more gases. Temperatures can be a difference too. 

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.