At the circus
We don't wear shoes in the house. This is unusual for the area we live. My husband, who was raised in a cold climate, has never worn shoes in the house. The reasoning for him was not to track in the ice, snow, and salt that were on the roads and sidewalks most of the year. He also made some very valid points about how taking off shoes would prevent most of the dirt from being tracked through the house. He had converted me before we ever had kids. Of course, I did have to do research once we would have babies rolling and crawling on the floor to confirm what seemed obvious. Not only was he right on it being cleaner, but I still learned something interesting. Everyone knows not to feed a baby (under age 1) honey because of the risk of botulism. Once a child is a year old the risk is gone because the intestines are fully developed and can fight off the bacteria. Botulism can be fatal for infants so this is extremely important. What I learned through my research is that most cases of botulism are caused by babies eating dirt or other things tracked into the house on shoes. 90% of cases are caused by this and yet the educational push in the U.S. is to remind parents not to give their kids honey, which makes up the other 10% of cases. So, we continue not to wear shoes in the house.
Playing in their kitchen
Once our children started walking, more research was done to determine the right type of first shoes. If they are too stiff the kids won't be able to walk in them. We went with two different brands, Pediped and Robeez for their first shoes. They both offer soft soled shoes. This allows the new walker to feel the ground and get better grip. It also helps with the gross motor development and balance required for walking and running. Once they are better walkers we moved into more traditional tennis shoes.
At the park
Same park (yes, he's that much taller)