@Jimmy56,
In Episode 109:
"Beaver must write a composition about his mother but soon finds himself the only one with a seemingly "boring" mother while Richard, Larry and Judy have colorful mothers. Beaver decides to make his mother colorful too even if it means making up things."
It sounds like the script writers were having pun with "colorful".
Guessing the teacher asked for a "colorful" composition and the Beaver, ever eager , complied.