The Natick Community Organic Farm has some great programs for children ages 3 and up. They have everything from Parent-Child programs like A Farmer's Morning, Scout Programs and Overnights, to Preschool and School Age programs like Chore Time (includes gathering eggs!) and Hop with the Bunnies. They also have very popular summer programs for ages 4-15, Mon - Thurs, mornings or afternoons. NCOF members receive priority registration for the summer programs - so become a member if you're interested - summer sessions fill up quickly. Lots of farm fun for the kids!

If you want even more nature class options, or if Natick is too much of a hike for you, try Puddlestompers.  They have classes in many towns.