To add individual notes when you correspond with someone about a student, put those in the Notebook, just like all of your other notes.
Select the type 'Correspondence', in the description, put the name of the person, and then add the details of that correspondence.
Then, if/when you're looking back at a particular week, you can see those communications in context with everything else that happened.
If you want to see an overview of your correspondence for a particular student, you can go back to their Correspondence page and it will list all of the people you've ever entered and notes from the most recent communications with them that you added to the Notebook.
Does that make sense?
Let us know if you have any questions or we can clarify anything or make it work better for your needs.