Split not returning an array?

Okay you're all right, before the split it's already "science students"
... how can I stop that from happening?

I'm pulling it in through a URL for a calendar/events site. The URL
determines what calendars to pull events from (ie science and students),
so I have params[:cal] that's supposed to store the string. Why is it
unescaping it for me?

Because it is defined in the specification for URLs that + means space.

If you want a real + in your URL, you have to escape it, e.g.

    http://localhost/foo/science%2Bstudents

(the same applies to a number of other special characters too)

When generating links dynamically in a page for people to click on, you
should be escaping them in this way.

Regards,

Brian.