Ultramarina, I also wondered about this. I never took anything beyond basic Chemistry, and Diff Eq were not required. Does this mean that in other countries kids take three semesters of Calculus and then Differential Equations before they attempt Chemistry?

I guess my impression was that in many other countries that math and science were not taught as distinct courses of Algebra I/Geometry/Algebra II or Biology/Chemistry/Physics, but rather a bit of each is learned each year, and perhaps the supporting math is learned alongside the science - but that you did not need a full blown Calculus course to complete HS science.