Impact of Class Size Reduction on Students

Dear Friends,

This week’s evidence comes from a forthcoming study by Chingos of the Urban Institute. The question is the impact of class size reduction on students. A recently signed New York law caps class size at 20, k-4; 24 5-8; and 25 9-12. California had already run this experiment in the 90s, and it was a disaster. Some students went four years without a qualified teacher. Why is this very popular law so bad? First, it’s incredibly costly with little evidence of return on investment (see Matt’s article at Urban Institute: How Will Implementing Class Size Caps in New York City Affect Funding Equity?). It will drain billions of dollars in funds away from real educational solutions, including paying top teachers the professional pay they deserve.  

Second, as California learned, there is not an unlimited supply of qualified teachers, so the impact of class size reduction was a very large number of students who had either long-term substitute teachers or teachers not certified in the subjects and grade levels to which they were assigned. While it doesn’t make John Hattie very popular, his massive database shows that teacher quality and specific teaching practices, such as effective feedback, have several times the impact on achievement as class size.  

While class size reduction is a popular campaign promise to win teacher votes, it is ultimately unsustainable. What you will find is unqualified teachers turning on Kahn Academy (see last week’s update) and other electronic aids that depend on students being sufficiently motivated to get the work done. Remember how well that worked during COVID?

I can be reached at 781.710.9633 or douglas.reeves@creativeleadership.net, if you want to discuss this week’s research.

Best,

Doug

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