Reading, Writing and Arithmetic.
A sample is a group of subjects such as selected from a population. A population deals with all different kinds of subjects that are being studied.
You get to learn at school. You have teachers that teach you all different kinds of subjects...
I know you can get many school worksheets of all kinds for all school subjects at schoolworksheets dot com. All the ones there are free to use and distribute.
English, Chemistry, Economics
Wikipedia has a wealth of knowledge on all kinds of subjects. See the related link for the main page.
perfect famlies, westerns
Pregnancy and sleeping arrangements, in the 1950s.
Shakespeare did not write subjects, he wrote plays and poetry. Those plays and poems address all kinds of different subjects, far more than you could list exhaustively.
He does not. He is dead. When alive he painted all kinds of subjects, flowers too.
Everything around him: people, things (still lifes), environment...
Pomology is the study of fruits. All kinds of fruits are studied under this subject.
There are many different kinds: epithelial, adipose, muscle, lymph, and many more.