組

1. Origins, structure, and basic meaning

• Structure: The noun 組, read くみ, means a group formed to work together or a numbered class at school.
• Basic usage: 三人一組 specifies a three-person team, whereas 二組 identifies school class two.

2. Common pitfalls and similar expressions

• A working group and a school class
  • It is used for a three-person working group and for a numbered school class. The number can indicate group size or the class label, depending on context.