You might want to try to catch a marionette show in the Théâtre des Marionettes in Jardin du Luxembourg. I have to admit, we haven't seen one yet, but we plan to. Last year, I thought the show began around 4:00 PM, and we got there only to find it over. I think there was probably another show, had we waited around. According to the following website, there are shows there on Wednesday, Saturday, and Sunday at 3 and 4:15 PM. Take the Métro Odéon or the RER Luxembourg. You'll find the little theater building about halfway back in the park... I believe it's near the Buvette de Jardin du Luxembourg... the snack bar. http://makeashorterlink.com/?Q1A212AD9

I also came across this pdf file of things for kids to do in Paris, compiled by members of the American community in Paris: http://www.amb-usa.fr/consul/guideoas/children.pdf

And a good article, with things for children to do: http://www.parisbreak.co.uk/leisure/kids.asp

Best, Sandy in Illinois