It baffles me that -- at least in the U.S. -- we don't include logic per se in the core curriculum of a liberal arts college (let alone high school) education.
As an undergraduate I took an "Intro to Formal Logic" course, found I really enjoyed it, and was invited to become a tutor in subsequent semesters. At the time (circa 1995) we used the 7th edition of a classic textbook, "Logic & Philosophy: A Modern Introduction". Doing logical proofs in sentential and predicate logic is a lot more fun than it sounds, and results in improved instincts and ability to determine the logical validity and veracity of any set of statements. This skill is profoundly useful, and has incredibly broad applicability. It helped me ace my LSATs, and enabled my transition to software engineering. I think logic per se should be a core requirement for any kind of decent education. And if you're looking to improve your critical thinking skills, this is the foundation. It's reason, distilled.
[Edited to add intro / context]