What is the purpose of covering a portion of the leaf with an opaque material?

The purpose would be to block photosynthesis for that portion of the leaf. The only reason for doing that is probably just to demonstrate photosynthesis to students. More.

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.