What languages (or classes (as in paradigms) of programming languages, plus a recommended language of that class) should every computer science student be taught in college according to you? Motivate your answers; why that language? What use will one have from it? What concepts does it teach (better than language X does)?

Note/clarification: This question is about computer science with heavy focus on software engineering, not pure computer science. It is still computer science education and not software engineering education which is the focus.