We visited Bismarck Zoo twice: once in winter and once in summer. The collection of animals is descent. Also, most of the animals are from the cold climate like bobcats, dear, buffalo, moose. There are also several tiny rare monkeys. In the middle of the Zoo, there is an educational pavilion with lots of information on bugs, bears, other animals. This was the favorite part of the Zoo for our kids. They looked at bugs thru the magnifying glass. Also, there is a table for kids, so they can draw some pictures. The Zoo is not very big; it takes about 2 h to go around. The thing I did not really like is that there is no food places inside. Sobe prepared to take you snack with you.
To summarize: from all ND Zoos we vizited, the Bismarck one is the best place to take kids.
We've been to big zoos and small zoos, and this one's a nice in-between. They have many species of animals, both native and exotic. The zoo itself is very shady, with lots of trees and grassy areas. A tram ride (at extra cost) will take you around the zoo and tell you about some of the animals. There's also a nice playground area and concession stand, so if they kids need a break from the animals, there's something else for them to do.
The zoo is part of a large park that has a lot of playground areas as well.