I am looking for books, articles, and websites that are basic introductions to the logic notation system created by Frederic Fitch. Recommendations welcome.
I learned Fitch-style natural deduction from Teller's A Modern Formal Logic Primer, which is freely available here. Teller goes through the motivations for specific formal decisions and outlines the strengths and weaknesses of formal reasoning. It's pretty good. I know of at least one intro to logic class that uses it as a textbook.