TITLE: Computer-assisted proof for undergraduates
QUESTION [7 upvotes]: Is it feasible (yet?) to support a (say) sophomore-level introduction to mathematical proof with an automated proof assistant such as HOL (or one of its variants), Isabelle, or Coq?
Can I find publications, pre-publications or lecture notes that introduce one or more proof assistants at a lower-division undergraduate level?
Of the many proof assistants out there, famous or not, which would promise the best experience for complete beginners?

REPLY [5 votes]: It's definitely possible. Jeremy Avigad and two of his PhD students, Floris van Doorn and Rob Lewis, taught such a course at Carnegie Mellon aimed at freshman- and sophomore-level undergraduates. The course was an introduction to logic and proof, using the Lean proof assistant.
The lecture notes they wrote for the course can be downloaded here (HTML version here).
See also Jeremy's page, Resources for Teaching with Formal Methods, which contains lots of other resources relevant to what you're looking for.
Lean is designed with accessibility in mind. It has very readable and relatively intuitive syntax, so would be a good choice for beginners.