当番

1. Origins, structure, and basic meaning

• Structure: 当番(とうばん) refers to a duty taken in turns or the person whose turn it is.
• Basic usage: A task can precede it to identify the duty, as in 水やり当番.

2. Common pitfalls and similar expressions

• Duty by rotation versus general responsibility
  • 担当 broadly refers to an assigned responsibility or person. 当番 particularly emphasizes a scheduled turn or rotation.
• Person or duty
  • 私が当番だ means that it is my turn to be responsible. 当番を忘れる means forgetting the assigned turn or duty.