Both stories and community posts have a small 'eye' icon which educators can tap to see who has viewed the content. For a more detailed understanding of family engagement, also check out activity reports.
From a service or room's stories page, each story's tile has the eye icon at the bottom:
This counter doesn't treat each user as unique but counts the sum all views, as we know that your stories are likely to be read by the same person more than once.
In the example above, only two names are shown but the counter shows the number three. This means collectively those two people have viewed the story three times.
The responses section of a community post also has an eye icon which educators can tap to see who has viewed the particular post.
Note: For room community posts you need to be added as an educator to the room to see this.