You're not stupid. I'm the exact same way. I always forget things and to prevent this I always take notes and review my notes every day.
Reviewing your notes every day will help you remember and retain the information better. Always take notes in class. Try to write down everything the teacher says, mainly the main points.
A good way to study for tests and remember stuff is to make flash cards or create mnemonic devices.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.