Complex sentence: The children were led into a room, empty of distractions, where a treat of their choice (Oreo cookie, marshmallow, or pretzel stick) was placed on a table, by a chair.
Split into simpler sentences: The children were led into a room, empty of distractions. There a treat of their choice (Oreo cookie, marshmallow, or pretzel stick) was placed on a table, by a chair.