The Responses feature of PublicLab.org now has a means to post a note requesting responses, which will only be shown on that page, instead of on the main user dashboard.
This is helpful in cases where an entire class might make postings on a specific topic, all at once -- it collects the responses in one place and sets up a button for students to click to file their assignments.
For an example, see this post: https://publiclab.org/notes/kanarinka/02-24-2016/assignment-reflections-on-sensor-journalism
Create your own request
To post a note that requests responses, click the following button. The "Post a response" button on the resulting page will automatically set up respondents' posts to appear below your post, and will also copy any tags on the requesting post. So if your class is about organic gardening, for example, add the tag "organic-gardening" and your respondents' posts will also be tagged as such.
See examples of this here: