My first education policy proposal
Jenny D asks "how do you know if a teacher is really implementing DI, or any kind of instruction?"
Most states (if not all) have alternate teacher certification programs. Often they revolve around content knowledge (especially in math and science).
Perhaps private organizations, such as the National Institute for Direct Instruction should create their own certification programs in conjunction with a forward looking state. These schools would directly compete with education colleges and schools in certifying teachers. Once certified in providing direct instruction, these teachers would be 100% certified to go directly into teaching without further training.
Of course there are many limitations, including opposition by teachers unions and the education establishment. The newly certified teachers would also need to find positions in schools that supported their methodology.
If school choice (competition) is good for schools, why wouldn't it be good for the institutions that produce teachers?