As part of her science experiment for her Child Psychology degree, Didt takes Tommy and the Rugrats to Kinyuka College, where she tries to find a way to make the Rugrats go to sleep faster, using a wind-up toy that plays lullabies. But when tests didn't work as expected, Didi tells Betty that she'll cry if she doesn't get an "A". This promoted the Rugrats to search the college campus for that elusive "A". (thetvdb.com)