How many stars are in the solar system?

The correct answer is one.

The solar system refers to a system in the universe that comprises of the Sun (a star), and eight planets orbiting it. The Sun is the only star in the solar system. The Sun is spherical in shape and has an extremely hot surface. Even though it is the largest and most visible star from the Earth, there are other stars in the galaxy much larger than the Sun. 

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.