Researchers have been testing content-packed lessons in schools to see how much they boost reading comprehension. A 2023 study of the Core Knowledge curriculum, which was not peer reviewed, received a lot of buzz. The students who attended nine schools that adopted the curriculum were stronger readers. But it was impossible to tell whether the Core Knowledge curriculum itself made the difference or if the boost to reading scores could be attributed to the fact that all nine schools were highly regarded charter schools and were doing something else that made a difference. Perhaps they had hired great teachers and trained them well, for example. Also, the students at these charter schools were largely from middle and upper middle class families. What we really want to know is whether knowledge building at school helps the poorest children, who are less likely to be exposed to the world through travel, live performances, and other experiences that money can buy.