The evolution of the DPS portfolio
If you ask Jennifer Holladay, Denver Public Schools (DPS) Portfolio Manager, why their portfolio approach has worked, she would tell you because "all boats [both charter and district schools] are rising and students and families have access to better options". She'd also tell you that they still have a lot to learn and that there have been many failures along the way.
In following the district over the last thirty years, we've seen the evolution of the portfolio from a weak example of managed instruction, through early authorizing to what it is today -- one of the leading models for public school collaboration and accountability.