is it ok to double space in a term paper?

It used to be. I don't see why it wouldn't still be okay. Did you ask your instructor if it was acceptable? Double spacing has always been used so the teacher can edit the work (make corrections, notations, etc.).

Isn't it required?

I thought most instructors preferred double spacing, don't they? Unless it's changed over the years.

I always double spaced in college. It makes it a whole lot easier to read

There must be guidelines on the formatting expected?

Aren't you suppose to? Google it.

I wouldn’t want to read it if it was single-spaced. I would resent you from the second line on.