M.P.
Starland in Deerfield offers a fantastic spanish class for 5 year olds. Call ###-###-####. The class is an hour long and meets once a week all semester and is perfect for kids who go to half-day preschool or kindergarten elsewhere. The class is taught in english with lots of games in spanish and conversational spanish, reading and writing being taught, and the teacher has more than 20 years of teaching experience with this age group. She is remarkable and her name is Marta. This would be a great first-step class to take before putting your child in anything really intensive that met more than one day a week. The starland class is educational but fun too and the kids love it.
Now there is also a regular school called Sherwood which I believe is in Highland Park... could be mistaken-- somewhere up there-- which is a regular school with a Spanish immersion program and all the kids' classes are in spanish. I teach enrichment classes and have students who go to Sherwood and they all and their parents, are very happy with it. The kids do seem to understand a good deal of spanish too.
Lastly, also in Deerfield there's a language arts summer camp and you can take the immersion summer camp in spanish. I don't know anyone who's done this camp but I have gone to the park this summer and seen the camp and watched them play games in spanish and heard them sing songs in spanish and it just looks fun and educational.