I'd like to read some papers concerning fundamental groups, for example, papers written to explain some basic facts about homotopy explicitly for undergraduate students.
All the papers I have requires many background knowledge (homology, for example) but I'd a paper for young students.
I know that there are many good books but usually in books we find the theory explained in a row, or in the order just to read and follow. I'd like to start some research on a low level .
Suggestions are welcome. Best wishes.