Summer school? Reading books? Camp? Computer games might be a better choice
trueslant.com
trueslant.com
http://www.ams.org/employment/mathcamps.html
are essentially free to participants, as they have heavily discounted list prices for everyone, and lavish need-based financial aid.
I was nine, and a friend had given me a pirated copy of the game. I was instantly fascinated by the campaigns and the background to the actual gameplay (at which I was pretty bad). I learned a lot about history in general, I loved playing around with castlebuilding or crushing an enemy with a huge army. I loved the evolving and changing missions, reflecting a real battle, more a long, progressing struggle with sudden interruptions and changes than a simple fight. I spent ages creating my own scenarios. I loved playing the game, and it shaped me.
Fast foward to the present day. I'm 17, and going to choose the specialist subjects for my final exams in 2 years. History is definitely going to be one of them.
Such is history.
I lost that game.
Which of these is best probably depends on the child: the game is likely to be less factual, and probably less insightful, but it will typically hold the child's attention better. That counts for something.