Sorry, I see too many posts on the tortoise forum from people who want a tortoise because they're cute, but they don't want to take care of it properly. I still maintain that a tortoise is not a good pet for a young child, partly because they don't like to be handled excessively, and it's hard for a child to understand that. If you are willing to take on the major responsibility, then a russian tortoise might work for you. They are very hardy, and you can build an outdoor pen for the summer (tortoises need to be outside as much as possible), then bring it in for the winter. They also don't get too big. Most of them are WC, though, so you would have to take in in for a vet check and probably treat for parasites.
Again, I apologize for being harsh. Tortoises and turtles are wonderful animals and I hate to see them being neglected.
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Sohni
Northern California
0.1 Baja de L.A. Rosy Boa
0.1 Okeetee Corn Snake
1.1 Rubber Boas
1.0 Leopard Gecko
0.0.1 Hermann's Tortoise
0.0.1 Marginated Tortoise
plus my kids' herps:
0.1 California King Snake
1.0 Mexican Rosy Boa
0.1 Leopard Gecko