Marking Participation

A classmate told me that in high school we are not allowed to mark for participation and I want to encourage us all to think purposely and thoughtfully about how we plan to assess students' participation in our classes. In one of the unit plans that we went over on Friday the authors constantly wrote that participation was not going to be marked but still noted. I really don't like that because it suggests that somehow a students' participation will be taken into account in an informal way. As a student I remember having such comments said to me and I would immediately become suspicious of what they meant. Was the teacher going to mark my assignments harder if I didn't participate or hold it against me as a personal flaw? Probably not, but it still made me worry. All I am trying to say is that we need assess thoughtfully and clearly so that students know what is expected of them.