Help Tinker Bell find all of the Lost Things in all five locations.
Lost Things are objects from the mainland (i.e. things that are out of place for a remote fairy island). There are 3-5 of these to collect at each location and a total of 19 in the episode. See THIS guide for all of their locations. It is suggested you get these as well as the sproutlings out of the way first when you start each location, as you can progress to far and complete the level without collecting them, forcing you to replay the entire level. Once you have gotten all the Lost Things in a level, you MUST complete the level for it to save them. You are missing Lost Things in any level where you did not earn the right star in the location-selection screen.