Often undergraduate discrete math classes in the US have a calculus prerequisite.

Here is the description of the discrete math course from my undergrad:

> A general introduction to basic
> mathematical terminology and the
> techniques of abstract mathematics in
> the context of discrete mathematics.
> Topics introduced are mathematical
> reasoning, Boolean connectives,
> deduction, mathematical induction,
> sets, functions and relations,
> algorithms, graphs, combinatorial
> reasoning.

What about this course suggests calculus skills would be helpful?

Is passing calculus merely a signal that a student is ready for discrete math?

Why isn't discrete math offered to freshmen — or high school students — who often lack a calculus background?