R.B.
If you literally have to create the skits from scratch, have the kids write them. Brainstorm topics with them, break them into groups and have each group choose a topic and write their skit. Don't be too fussy about the quality of their skits, they don't have to be perfect -- the most important thing is that the kids are engaged in writing and performing their skits, and they will probably come up with some pretty good skits. You can monitor and assist when necessary.
I had a lot of success with a book called 111 One-Minute Monologues by Janet Milstein. There are updated versions of this book. It has comedic and dramatic one-person monologues, however, you may be looking for group skits only.