So, that's 25%

In a follow-up to this post, I wanted to find this post, from Nashville Jefferson. Here's why. I wanted to see how much school-based variables impact student achievement. His post makes clear: 50%. That means 50% is beyond a school's control. But it also means that if we assume that teacher quality accounts for 50% of the school-based variables impacting student achievement, it means it only accounts for 25% of the total impact on student achievement.

Sure, that's a reasonable amount. And yes, we should be concerned about attracting and keeping the best teachers in the classroom. But we shouldn't forget about other factors.