This idea has been very popular at my school so I thought I'd share it with the community. Teachers are choosing a twitter feed to embed in their Canvas page (a favorite for humanities teachers is CNN breaking news) and then having students post to discussions or write about one of the tweets as a brief opening activity. Because the feed is always updated, the options for writing change with the news. And because it is embedded into the Canvas page or discussion description, students don't get distracted by tweets from their friends or favorite celebrities.
This has sparked a new interest in current events among the students and gets students focused as class begins.
Here's a screenshot of how I have used it in my 11th Grade Humanities course: