Just as in math there is an applied and theoretical aspect, there is in CS as well. There are plenty of great opportunities to us calculus in stat, econ, physic

Just as in math there is an applied and theoretical aspect, there is in CS as well. There are plenty of great opportunities to us calculus in stat, econ, physics and so on, but calculus can be a great introduction to proof writing itself. In the same vein algorithmic complexity can be a fantastic first gentle introduction to theory and it's best when tied into writing algorithms in a data structures class. The same can be said about regexps for example - practical v theoretical aspects - or logic as applied with prolog (or even make) say. The interesting thing (as seen in a comment below about arrays and constant big-O) is that often intuition goes against the the rigorous understanding - so it's best to have both. I suspect the same holds for language as well. For example etymology of word roots as well as actual writing using the words.