The Cloud Appreciation Society seems like it could have a link with classrooms.
Perhaps I'm partial because the weather in Brussels has gotten so nice - it has been a warm, sunny weekend to end a warm sunny week, during which we went to the forest three times and kept our classroom windows open. I can imagine children photographing clouds, and using the photo gallery "Clouds That Look Like Things" to share their findings. What an amazing oral language activity, too, for children to have conversations about what they see and to talk about similarities and differences between the different kinds of clouds.
I think that cloud photographs would be a great starter for sketchbooks one morning - every child feels confident enough to draw clouds, and some children might even enjoy drawing an object as a cloud.