Just a minute after this quiz, if someone were to provide the answers and descriptions of what had to be written and asked me to write it in Lisp, I'd probably get 2/7 or 3/7, covering only the simplest of examples.
That's probably because the first few steps are very incremental. It skips ahead faster after that. If you were to make a longer version of this that was more gradual, I think people would be able to pick up more advanced concepts correctly, although it would definitely be much longer.