Formal:
* Chn. (common in lists, tables, etc.)
* Kids (informal, but widely used)
* C. (rarely used, can be confusing with other abbreviations)
Informal:
* Kids (most common)
* Lil' ones
* The little ones
* The youngsters
It's important to choose the abbreviation that is most appropriate for your audience and context. For example, "Chn." might be suitable in a formal report, while "kids" would be more appropriate in a casual conversation.
Remember, using abbreviations sparingly and clearly helps maintain readability and understanding.