Throwing Kindness like Confetti in the Classroom

We have started an initiative in class to spread kindness to each other.  We have had several 'kindness' assemblies throughout the year and classroom discussions.  During one of those assemblies the 6th graders had made this huge bulletin board in the cafe that says "Throw Kindness Like Confetti".  Students then wrote on post-its about certain aspects of kindness they observed.   
Taking that idea, I found some motivational, inspirational, and kind cards that I printed out on colored paper and gave each student in class.   There are more than 20 cards of all different sayings.  They then had to number their envelope 1-20 (excluding themselves) and use it as a checklist for each student in class.  The challenge is to write something kind to everyone in class at some point in the next few weeks.  They can't just give a card, they need to write a message on the back.  
These messages have been unreal.  I was literally in tears this morning reading some.  They have really taken to this activity and have been very thoughtful in their messages to their peers.   I hope they are able to continue to spread kindness to others, beyond what is expected of them.  :)