I certainly understand your desire to use some fencing for safety purposes. Not only will fencing keep your children and dogs in a confined area, but it may keep another dog from having easy access to them. I guess those folks commenting above don't have a lot of experience with kids and don't know that even if you're outside with them, they can take off very quickly and get into trouble before you can even catch them. Personally, I'd rather they be confined behind a fence instead of charging after a toy or ball and being on a campground road in a blink of an eye.
We use two of these to make an 8x8 pen for our doggie when we're allowed to use it. Of course, when the dog is outside in her pen, we are outside with her to make sure she doesn't start barking.
Exercise Pen.