I have 3 DC, DS1 is almost 9, DS2 is 7 and DD is 5.
We are doing:
The summer reading challenge at the library. DS2 needs no encouragement to read (he finished his first book within 24 hours) but I am hoping that it will help DS1 develop the staying power to stick with books all the way to the end rather than just dipping in and out, and it gives DD a bit of structured practice. They also write book reviews as part of it, which keeps up their writing.
MathsWhizz. I have signed up for the free trial, maths isn't DS2's strong point but he loves computers so I'm hoping that it will encourage him. We also have some maths workbooks which DS1 and DD like to do, but DS2 is not so keen.
Nature Detectives (see mrz' link). We also do nature activities at our local RSPB reserve, nature reserve and forestry commission site. Even when there aren't structured activities taking place these are great places to visit.
DS2 loves history. We visit the local museum a lot, and went to the National Museum a couple of weeks ago. Over the summer there are activities as part of the Festival of British Archaeology which we will take part in. We will also go to a reconstructed Iron Age Hill fort near us which has a lot of summer activities run by the national park showing how Celts used to live. There is also a castle nearby which is a national trust property and has a weekend of archery and falconry!
Before anyone tells me that holidays are for fun these are all activities which have been chosen by my children. They still spend a good deal of time playing football, running round the park, watching DVDs etc. We have 7.5 weeks off for the summer so there is plenty of time for a bit of everything 