 So the evidence you use to answer your teacher question is evidence agreed upon ahead of time. That if you want to know, for example, if that turner is a hero, then you want to have evidence in there that kids have to work with, right, about that. So that turner's confession, right, a list of people who are killed during his raid and teachers are going, kids are looking at going, I can see why I want to do it, but, oh, there was little kids, babies who were killed as partners. What is that, you know, how to grapple with that? So it forces, the question forces also the lesson to be deeper, I think, because you have to build into the lesson places where evidence will be generated to analyze. Well, as Stan said, it's sort of a perfect medium for bringing historical knowledge into the classroom because one really cannot do topic-free, subject-free, content-free lesson study. It has to be about something. And so as teachers develop their lesson, they are often going back to the drawing board and making sure that they understand the history very well. They're often considering which documents or images are they going to be presenting to their students and therefore they're doing quite a lot of research. So their content knowledge is being very well developed throughout the process. Despite that, it wasn't our big first goal with it, but through lesson study, teachers are delving into content much more deeply. They're learning more content. Because the process of writing a lesson that is appropriate for lesson study, that is one that's, as you described, focused, that is sort of well coordinated between the research question that has to then, and the student question which then has to be answerable, you're setting up a kind of a tight structure for a lesson. And teachers have to be able to get to the essential of the matter and to learn to be concise. And as you know as an historian, you have to know a lot to be able to get the point across concisely. Part of learning history or becoming more thoughtful history is not just the content, it's the thinking that goes with it. So understanding history is a subject that has interpretation, that has ideas of significance, that works with evidence. So as you begin to debate among a group of teachers, what topic you're going to teach, it's really a question about historical significance. Why is this topic worth teaching to you? Why is it worth spending time on? I think that's another piece of the content. Because I would add historical thinking to historical content as a whole piece. So it's not only that teachers are trying to encourage their students to develop historical habits of mind, but they themselves are cultivating their own historical thinking. Then what we learned over the first couple of years was the teachers were very used to planning lessons. And so they spent a lot of time planning lessons. And one of the problems with a challenge lesson study is there's only a certain amount of time, people have time to collaborate. You can do something for a certain amount of days, but you can't get everything together for a long time. It's got to move reasonably quickly through the process of planning. So they spent a lot of time planning, but the part which was the most powerful, the analysis part, got short shrift. So we kind of produced a video where we followed a couple groups of teachers, fifth grade, through the analysis part, to give teachers an image of what that looked like. And so here's where we're headed. So we got to get there, right? So that's been very helpful. But we've kind of tweaked and added to it all through the seven or eight years now to kind of take each step like this. At Carol, there's a planning step, and then there's a teaching step, there's an observation step, and then there's an analysis step, to go, okay, in each part of that, in each point along the way, work we deepen, experience so it becomes professional development in each part.