I have an Excel spreadsheet in which we use to keep track of online courses
we work on each semester at work. So far, I've been able to use the COUNTIF
function to calculate the number of hours it takes to work on a course using
a drop-down list that I've created.

I would like to add some additional data to my "Reports" tab that would
calculate the number of courses that we work on for a specific date range
(example: from January 1, 2007 to March 15, 2007).

Further, is there also a way to tally this information if I have multiple
tabs on my spreadsheet that contain similar data?