Are you doing anything to keep school skills sharp this summer? My DH decided Lara had to research and write little reports every two weeks on subjects he has dreamed up. The first one was "Andre Segovia and me - how are we alike?"
My DS (9) has to do a math worksheet every weekday (about 10 minutes of work), plus at least 20 minutes of reading.
My DD (13) has to do a math worksheet, one Spanish lesson, practice piano and read. The reading and piano are actually fun for her, so it's not too difficult to get her to do it.