Genesis chapters 1-11 present simple realities about God, us, and our relationship to him. In a sense, we find the central core of absolute truth in these chapters in the form of timeless and central realities our children can understand. These are truths that we are responsible to teach them, to show them.
If you've never read Shepherding A Child's Heart by Paul Tripp, perhaps it's time to pick it up. Parents are called by God to shepherd their child's heart and not just manage their behavior. Kris Schaal will give you 6 reasons why you should read this book.