I think the best way to help kids with writing, especially when they’re stuck, has less to do with actual writing skills and tools than it does with remembering that they’re trying to express themselves, as we all are. They’re trying to get what’s in their heart or in their brain onto a piece of paper.
Rather than trying to correct their grammar or their sentence structure during that phase of writing, I think it’s much more important to listen to them and ask them, “What are you trying to say,” and to say to them, “Ask yourself what is important to you about this story? Who is the character that you’re talking about? What does he or she want? How is he or she going to try to get it?”
Just ask them that and let them answer it. Let them talk and let them explore what the answers to those questions mean, and then just let them write and don’t correct it yet. Just let them write. Give them permission to write a bad first draft, because the point is to express yourself and to get what’s in here onto the page.