We have 2 new puppies--3 months old when we got them, now 4 mos old. When they're let out to go potty ...?

and play, they never venture far from the deck. However, when our 3 kids go outside with them, the dogs, especially the male, will put his nose to the ground and go go go. I have to chase him down from 3 or 4 yards over. (and we all have pretty big yards where I live!) My question is WHY does the dog feel so free to wander off when the kids are outside, but when it's just the dogs outside they only care about playing with each other and stay close-by. This is getting very frustrating. Thankfully, I only have to wait till the ground has thawed enough so we can set posts for a fence!!