In the 1960s, a man named Siegfried “Zig” Engelmann set out to answer a question about how kids learn: How many times does a child need to be exposed to something before they remember it? Engelmann ...

This is one of the reasons that teaching can be so difficult. You have to overcome what's known as the “curse of the expert.” Once you know something, it's hard to remember what it was like to not ...