$20-$30 billion. That's one estimate at least for what districts are spending each year on professional development posed by Doug Lemov and Co. in his new book, Practice Perfect: 42 Rules for Getting Better at Getting Better. 

Practice Perfect explores how the simple act of having teachers practice their craft can lead to transformative success -- but only if executed correctly. Lemov had observed that successful teachers practice them relentlessly. Which is unlike current professional development -- in which teachers "listen, reflect, discuss, and debate, but they don't practice." Here are some key takeaways for schools and districts to extract real value for their money spent on PD:

• As a starting point, recognize the difference between simply doing something repeatedly -- which can encode failure instead of success -- and mindful, focused practice.    

•  Adhere to the 80/20 rule: spend 80 percent of time working on the 20 percent of skills that are crucial to  success, instead of choosing a new focus for each PD session.

• Provide immediate feedback and opportunities to practice the skill again as soon as the feedback is received. Teachers shouldn't just work on a skill until they've got it; they need to work on a skill until it becomes second nature.

Implementing these guidelines does involve a cultural shift because it assumes that teachers have the support of their principals, mentor teachers, and fellow teachers in an atmosphere in which practice is a natural part of every day and not seen as completed at the end of a PD session.  As the authors point out, teachers want to learn and improve; districts should make it easy for them to do so, especially as new evaluation systems lead to more detailed prescriptions for remediation through PD.

Ruth Oyeyemi