I'm trying to figure out when it makes sense to transition my son (and daughter, eventually) from Lego to Duplo (or the equivalent generic blocks).
I'm focused on the age at which children have the manual dexterity, fine motor strength, and focus to work with the smaller pieces.
I'm not concerned about choking risk, which is why the recommended ages on the boxes are of little help - they're almost always driven by the unsupervised "put it in your mouth" risk, and I'm interested in situations with a high degree of supervision and a child who no longer puts non-food items in his mouth.