My last nanny was really outstanding.
The trick to getting good work out of nannies is to have your toddlers constantly ask the nanny to help them.
Toddlers can ask a nanny to show flash cards (Thinking or Communication), teach blocks (Thinking or Movement), read a book or play with dollhouse (both Imagination), give a bath, give food or drink, help with potty, teach dance, and so forth.
However, if the toddler doesn't ask, the nanny may not do nothing. I found nannies useless with nooboos but toddlers can get adults to do so much for them!