Facebook this week started rolling out an update to Groups that allows you to view who has seen each post. If you don't see the functionality yet, don't worry: it's a gradual rollout like all of Facebook's new features.
How do I know who's seen each post in a group? The check under each post indicates how many group members have seen it. This way you can stay updated on the group's activity. Hover over the check to get an idea of who's seen it and when. Anyone who can view the group post will see the check.
Notice Facebook uses the word "seen" as opposed to "read." That's because this feature is slightly flawed. Let's check the Facebook Help Center again:
What does it mean if a post in a group or message on Facebook is marked as "seen?" Facebook Messages and posts in groups are marked as "seen" after your friends or group members have seen them. Just keep in mind that if people see a group post or message, it doesn't always mean they had the chance to read it carefully.
This "seen" concept is much more useful in Messages than in Groups. The feature became available for personal messages on the social network a few months ago; it first arrived with Facebook Messenger 1.7 and was then expanded to all Facebook Messages. Again, that's also a gradual rollout: if you don't have it, that's just because Facebook hasn't given it to you yet.
Overall, I find "seen" particularly useful on mobile, which is when I most often need to know if someone has read my message. With Groups, I just don't think I'll be using it much. Nevertheless, Facebook offers a decent pitch via an example: a soccer team using the new Groups "seen" feature to make sure everyone knows when the next practice starts.
Still, many Facebook members are part of Groups with a large number of people, and even more messages. Sometimes users simply open a Group and scan the messages in a few seconds or less. They may not want to inform everyone else they checked the Group.
As such, I expect a lot more backlash from Facebook users for this one, especially given that this feature cannot be turned off. Privacy advocates are likely already trying to figure out how they can legally punish Facebook for skipping out on such an option.