If you're a high school teacher looking to foster an interest in how languages work, consider getting your students involved in the North American Computational Linguistics Olympiad. The puzzles are really interesting, and the top performers go on to International Linguistics Olympiad. If you're a high school student who's interested in languages and puzzles and you can't find enough interest at your own school, you can also go to compete on your own (assuming you live close enough to one of the sites).