To share with everyone, with a group, or not to share are considerations with all online media and maps are no exception. An ArcGIS Online account for schools offers all these options. Audience is the primary consideration in determining sharing privileges.
The Story Map Tour below is an example of an embedded Story Map. Since this map has been developed to be embedded in a website, the map has been shared with “everyone”. A stroll through Springfield Illinois’ Memorial Gardens in full fall splendor inspired this Story Map. This is a link to more information about embedding Story Maps: https://blogs.esri.com/esri/arcgis/2016/11/07/embedding-story-maps/