The Last Mimzy (2007)

Two children discover a mysterious box containing some strange devices they mistake for toys. As the children play with these "toys," they begin to display higher and higher intelligence levels. Their teacher tells their parents that they seem to have grown beyond genius and their parents, too, realise something extraordinary is happening. Emma, the younger of the two, tells her confused mother that one of the toys, a beat-up stuffed toy rabbit, is named Mimzy and that "she teaches me things".

Official website: http://www.mimzy.com