Simplify the following text for a Grade 3 native English-speaking person.
Original: A futon bunk is also arranged like a standard bunk except the lower bunk will be a Western-style futon couch which converts into a bed rather than a standard mattress .
Simplified: Metal poles or wooden beams connect the bottom bed ( called the bottom bunk ) to the top bed ( called the top bunk ) . A ladder is used to get up to the top bunk .