Creating a post in Google Classroom depends on whether you want to make an (for the Stream) or an assignment/material (for the Classwork page). Option 1: Create an Announcement (Stream Page) Best for: Updates, reminders, and quick announcements. Go to classroom.google.com and click your class. On the Stream page, click "Share with your class". Type your message.
Use + Create > Topic to organize assignments into units. To make sure I give you the best advice, are you trying to: Post an announcement for all students? Create a graded assignment with a Google Doc? Create a poll/question ? google classroom
Within the Assignment window, you can select specific students to differentiate work. Creating a post in Google Classroom depends on