Ellen Griswold mentioned the Chellburg Farm in Chesterton. I wanted to add that on Fri, Sat & Sun you can help feed the farm animals between 4:00-5:00pm. There are several nice trails near the farm too. You can walk from Chellburg to Baily Homestead. If you go Sun you can tour the historic buildings and learn about the local fur trade & farming in the 1800-1900`s. - not sure if your daughter w/b interested in the actual tour but she might enjoy the hike.
There is also the European Market in Chesterton. My kids always liked people watching, buying cookies
The County Line Orchard is nice. There is another place we really like but I cannot remember the name...it's just south of rt 30 I believe on Randolph. (We go every year and I still cannot remember the name! We haven't gone this year.) They have a nice hay ride and a few small attractions for the kids. I just heard this place was unable to open becuase they were hit so hard by the flooding. It's a shame...they seemed like a really nice family and put so much work into their beautiful property and the whole experience.