This activity is designed to be used as a mini lesson or to complement one for any writing convention. Students look through their independent reading material for examples of the focus convention (commas, periods, capitals, apostrophes, quotation marks, colons, suffixes, prefixes, ...) and work to determine the rules as to when and how to use it.
The class then shares and discusses their findings. Learning can be solidified by making an anchor chart to be posted in the class.
This could also be used as an independent activity, possibly in literacy centres, although I would recommend still discussing as a class and creating an anchor chart after everyone has finished.
I also have a spelling rules activity that matches this one: