Why I let my kids play in the dirt, and you should too

It was early noon on a hot summer day with temperatures nearing 95 degrees when I took my 3 and 4-year-old sons to a local farm to burn off some energy (and hopefully wear out for a good nap!). They immediately did what all boys always do and found the biggest puddle of water and mud. While all of the other children were content, or so they seemed, digging and playing in the sand pile next to the puddle, my two boys looked up with those big blue eyes and pleaded to play in the mud.