M.S.
Hi J.!
What a great parent you are for helping your daughter be responsible and prepared for babysitting!
Last I knew, the Red Cross offered babysitting classes for a fee. I think the Boys and Girls Club does as well. Another option is Overlake Hospital. They often have courses offered through continuing education. You can call the main switchboard and they can help you. It's possible some of the other hospitals like Children's or Evergreen offer classes as well.
Good luck, hope this helps.
UPDATE: I just had a thought. Maybe if you go to amazon.com and search by topic you might come up with something. For example if you type in the search bar for "books on babysitting" you might get a list of books that amazon has. If you don't want to pay for shipping, then you can always take the title of the book you want to your nearest bookstore and have them order it for you.