You can post announcements to the class stream to keep students in-the-know about class happenings. Announcements are posts that don't have an assignment. Use them to share updates or notify students of important activities. By default, students receive an email when an announcement is posted; however, students do have the ability to turn this notification off.
Everything on the class Stream is listed in chronological order. Unlike the Classwork page, where you are free to click and drag to arrange things in any order you want, the only option you have on the class Stream is to move a post to the top.
Click the More button for the post you want to move.