There seem to be a few studies like this that have evaluated scratch over the course of 10 classes, but they've been largely inconclusive beyond the "general en

There seem to be a few studies like this that have evaluated scratch over the course of 10 classes, but they've been largely inconclusive beyond the "general enjoyment" factor - http://scratched.gse.harvard.edu/sites/default/files/wilson-moffat-ppig2010-final.pdf http://scratched.gse.harvard.edu/sites/default/files/wilson-...