Larry Ferlazzo shared this John Hattie video on his blog, noting that Rick Wormeli shared it with him. John Hattie is an Auckland professor who researches the different influences on student learning from class size to student disruptions. In this video, he argues that when people suggest that class size improves student achievement, they are making a mistake (he calls it the stupidest, craziest, most puerile argument). He says that they are comparing it to the zero point, smaller versus larger classes. Instead they should be comparing class size to all the other influences. It's an interesting argument that will make sense as you listen to the first five minutes.