Negima!? Magister Negi Magi Episode 19: It`s Great to Go Back to Being a Kid Again and Having Fun. Although, I Can Have Fun Without Going Back to Being a Kid, Too.
Episode 19 of 26 of Negima!? Magister Negi Magi, aired February 7, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
With almost all of class 3-A in Suka form with child-like behavior, Negi becomes a babysitter.