Another one to agree with Minimu and Fran - no breed can be said to be good or bad with children. An individual dog may or may not be suitable for your family. Part of this will depend on your lifestyle, time commitment and the age/character of your DC, along with the age, character and breed of the dog, so every situation is unique.
In any case, you should not have a dog with small DC unless you are 100% committed to the hard work involved, particularly teaching your DC that your dog is not a plaything, should be respected and should not be prodded, poked, teased and pestered.
I would also add that although every dog is different, some breeds (in fact, many) require very serious levels of commitment for training and exercise not just a gentle saunter on the school run. For collies, labs, many terriers, dog such as Dalmations, Vizslas, setters etc, you should be looking at a minimum of 2 hours a day, probably with additional training, espcecially for collies. So it's really important that all the adults in the family are committed to making it work and are willing to put the time in (as well as being happy with the financial commitment).
We've got greyhounds, so they can cope with a relatively gentle 1 hr daily walk plus they go running with DH, plus longer walks on weekends and classes/activities on top. This would leave a lab or Wei climbing the walls though.