Getting good news home is a really important event for all parties.
For the teacher it not only helps to show the children that you really have noticed, but that you also consider it important enough that you will want to contact their parents positively, when often it's only the negative stuff that gets sent home
For the School it shows the children that teachers are really looking for the good in what they do and it gives them something to aspire to
For the student it gives them a sense of value and a bit of respect as well as a different view of their teacher. It also may change some of the conversation that goes on at home
For the parentit lets them know that the teachers are looking out for the positive aspects of their parenting and allows them to engage with other members of the family with a documented reference to the behaviour
The process can be as simple as sending the green sheets home with the child or perhaps making celebration postcards and posting them out. Whatever the approach, the documentation has to show value by having the date or period, the child's name and why they are receiving the award. Many children will choose to keep these awards safe for future reference.
Frequency should be as often as is possible, but at least one per half term and preferably per month. There is little point in making the award a once a year or once a term event and then for only the elite students, that just doesn't work as motivation for the majority, green sheets can go out as often as 10x a week for an up and running SBM school and they really do make a difference
Paul Dix of Pivotal education talks about the benefits of using send home sheets here