Especially in introductory classes at large universities, crossword puzzles can be a gratifying icebreaker, helping students to introduce themselves to each other and creating a more relaxed atmosphere. This effect is enhanced by making the puzzles a team project. If such classroom dynamics are not what you need, however, then save some class time by handing the crossword out at the end of the hour. The puzzles could still be assigned as group projects. You might do your students a favor by doing so, since the people who study student orientation to university life report that working on group projects is an important means of breaking the isolation and alienation that can plague undergraduate life.
Excellent software is available for generating crossword puzzles and clues.
I use Crossword Creator 5.0, shareware for which you pay less than ten dollars. If you like the shareware, you are morally encouraged to pay a few dollars more to the programmer. When I did so, I was supplied with a helpful manual and the useful Crossword Clipper for Windows, which allows me to cut and paste crosswords and clues into documents such as this one. Creating crossword puzzles with Crossword Creator is easy and enjoyable. I center a list of words into the Edit Bank, then command the program to Auto Place them in crossword puzzle format, and then enter Edit Clues mode to create a list of clues for them.