Megawords 1-6 student wk.bk. can be older edition

[Jill in Maine]

I'm looking for the Megawords student workbooks. I have T.E. and one copy of books 2-6, but will be teaching two students with this program. My set is the older edition, but I would take old or new since there seems to be very few changes made.
Thanks!
Jill