There are different types of loss, and they can be more difficult for younger people to cope with, especially when it's the first time, or if they haven't been modeled any ways to cope. The ending of the school year may be a loss for children. Some kids find school to be the most consistent part of their lives, so to lose it is can be something difficult to work through. Memory books can help document an important part of a child's life where struggles and successes are identified, and positive things are especially remembered. This can help a child learn that although the (person, school, event) is gone, these memories are still here.
Death and Suicide can be major losses where we start thinking about all the things we didn't get to say. Writing a letter can help transfer heavy emotion to something tangible. Reading the letter (optional alone or with a witness) can also be an option where it can help make the act more cathartic. Another step after writing and/or reading can be to have a ritual where you burn the letter in a safe area like a fireplace. This can help create a sense of closure.