Overview
Jack-Jack Attack is a 2004 American computer-animated short film written and directed by Brad Bird and produced by Pixar Animation Studios. It is tied into and included on the DVD release of The Incredibles.
The idea for this short came from an idea for a scene originally considered for inclusion in The Incredibles; it was cut from the feature and subsequently expanded into this short. The short revolves around the situations between Jack-Jack and his babysitter Kari McKeen (who was hired by Violet and Dash to watch Jack-Jack) during the events of the main film.
Plot
Rick Dicker, a government agent assigned to aid "supers" in maintaining their anonymity, interviews Kari McKeen about the events unfolded while she was babysitting Jack-Jack Parr, the youngest of a family of supers.
Kari begins by stating that she received a call from Helen Parr, who expresses reluctance about allowing Kari to babysit. Kari attempts to reassure her that she is more than capable of taking care of Jack-Jack, but the conversation is cut off by Helen's jet being fired upon. Thinking nothing is wrong, and that they were simply cut-off, Kari turns her attention to Jack-Jack. She asks him if he is ready for some "neurological stimulation" and plays the third movement, the Rondo alla turca, of Mozart's Piano Sonata No. 11 for him, which results in Jack-Jack having an epiphany about his latent superpowers.
From Wikipedia (CC BY-SA 4.0).