Big Sister is a song sung by Dora and Boots to show that Dora is indeed a big sister.
Lyrics
Dora: I'm gonna be a big sister
Both: Big sister! (x2)
Dora: Big sister, I'm gonna be a big sister
Boots: She's really good at caring
And she's really great at sharing
And she's loves to help everyone
Dora: I'm gonna be a big sister
Boots:I'm gonna be a big monkey brother
Both: Big sister (x2)
Dora: Say it with us
Both: Big sister! (x4)