Aliza is a background character whose name was revealed in the What's Your Favorite Word? interview she gave when she was 11 years old, at which time her favorite word is "sweet".
Sweet Aliza is a natural nickname for her, to tell her apart from the "Acting Aliza" who has the same first name and age, but a difference appearance and interest.
Dodgeball girl looks similar to Aliza, only a little bit younger.
Interview for WYFW[]
My favorite word is "sweet". If I get a good remark on a test, I'll say, "sweet!" If I get a good score at a dance competition, I'll say "sweet!" If something good happens in my family, I'll say, "sweet!" When it comes to my favorite characters in WordGirl: WordGirl, sweet! Captain Huggy Face, sweet! The Butcher? Not! The word "sweet" fits so many things.