>> we actually succeeded in that. we signed a contract in washington, d.c. where tenure seniority and lock-step pay are no longer issues. and 80% of the teachers who voted for the contract voted in favor of that. >> how do you differentiate? you talk about differentiating good from not so good? the critical measures are what, numerical, tests? is it subject of evaluation? >> yeah, the number one factor in evaluating the teacher has to be whether or not they're effective at moving student achievement levels forward. and that means that you have to look at standardized test scores. now, that should be the only measure? no. but it should be the majority of what you look at. you also want to look at their classroom practice. so go into their classrooms and see whether they're engaging kids. >> you use tests. you pay the ones who are better more. you fire the ones who are no good. >> that's right.