How Do We Know What to Teach

Ever wondered if our kids are learning the right things or how teachers decide what to teach? Well, in ND this is more or less is left up to the individual schools and districts and guided by the state.
Currently teachers are still trying to figure out what standards will be tested in the fall while preparing and planning for the shift to the Common Core in about 18 months.
Many different strategies and theories float around regarding how to tackle this transition.

What are your thoughts on how to tackle it or what things kids need to know in order to be ready to tackle the world outside the school yard?