1. which ancient astronomer developed a geocentric model of the universe explaining the observable motions of the planets?

a. aristotle
b. ptolemy
c. copernicus
d. newton

2. aristotle concluded that earth was round because

a. it always casts a curved shadow during a lunar eclipse
b. he sailed around the world
c. he calculated earth’s circumference
d. it exhibited retrograde motion

3. the first early astronomer to propose a sun-centered solar system was

a. galileo
b. newton
c. copernicus
d. brahe

1. B. Ptolemy
2. A. it always casts a curved shadow during a lunar eclipse
3. C. Copernicus
hope it helps

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.