Looking for Real Problems/Examples to Help Learn JS

I'm trying to help a friend learn js. He's working on codeacademy and also on khan academy but he feels like he's being rushed.

What hes looking for is some problems(/koans?) to help him really develop each concept he's learning-- whether its variables, arrays, etc.

There HAS to be a list of problems out there somewhere to help develop ones skills within each area of study. Have any of you come across one/made one?

Any recommendations? Thx