I grew up with Shelties. They are wonderful with kids, smart, affectionate and great companions. They do need a lot of grooming, those long coats will mat.
The one we had first was Frisky. He was actually bought for my youngest brother who was five, but the following year Mom was pregnant again so there was a baby in the house soon after. When Judy was 3 or so, she used to ride her tricycle in the house and Frisky hated that thing. He barked and chased her all the time. But when she took a corner too fast and started to tip over, he jumped on the back and his weight righted the bike. I saw that myself.
The last Sheltie Mom had was Mikey. He got pretty big, he had long legs and was probably about 45 lbs, so make sure you know what you're getting.
Cheri (Bubbee to Emily and Nathan)