Suggestions, anyone?

HELP!  I am looking for suggestions for activities to occupy hubby's 3 grand daughters (9, 4, 3) when they come to visit in a week or so.  He typically doesn't "do" much with them except take them fishing to a neighbor's pond.

 Last year, I had each of them decorate sun hats for themselves and one for their mom one morning while their parents and my hubby slept.  Then another morning, we made a summer dessert together.  Then it was bug hunting.   

  So, come on all you crafters...give me some ideas so I can prepare!