[6AA4FD]

I've used forall x (calgary remix), both the winter 2018 and the spring 2020 editions, and I found it quite good. It teaches truth functional and first order logic, and it's probably accessible to most high school graduates. I've seen it taught with good results to students of different academic backgrounds as a 'math' course for general education. I've linked it below and it's free (as in beer and as in freedom) so it's definitely worth glancing at, along with the rest of the open logic project.

http://forallx.openlogicproject.org/