When all the students are present and marked as such on the attendance page, the check marks show up on the current day. However, on the check marks disappear after the date. Yet, if a student was late or absent, then all the various marks continue to show after the date. The problem with this is then I am unsure if I forgot to take attendance or if all the students were present.
So in the image below, the current date is September 15 and all the students are here. All the students were also here on September 12, 13, and 14 as well, but attendance marks do not show up. On September 11, a student was absent and the attendance marks show up.
It would be nice if Schoology would change this so that the check marks show up on days when all students were present and not just when there was a late or absent student.