Actionscript 3 :: Class Organization: Function Internal Or External?

I am creating a side scrolling game in Flash (as3) and trying to keep things organized and clean.Ive created a "Level" class that gets all the level data, player data, and creates all the terrain objects and the player object. Its starting to get messy because im handlng all of the functions for player collision checks and player movement, terrain movement, sound starting and stopping, enemies, and more, all in this class. Is this normal? Or is there a better way to organize things to keep them separate, but still allow them to interact with each other.