Curators with the Smithsonian Air and Space Museum are in the process of scanning the spacecraft for its digitization project with the goal of creating the most complete model possible. But they found something interesting in the process.
At some point during the flight, one of the Apollo 11 astronauts drew a calendar on a section of wall below one of the storage lockers. As each day passed, someone crossed off another dated square on the wall. Since there's no day and night when mission elapsed time is just cumulative hours, I suspect they marked the end of a day at midnight Houston time. The only day on the makeshift calendar that isn't crossed off is landing day, July 24.
Finding a calendar with the days crossed out makes it look like the astronauts were counting down the days out of frustration, boredom, or because they weren’t having fun (at least that’s why I used to cross off the days until the start of summer holidays). It’s very unlikely that’s the case. I’d wager they did it to have a sense of what day it was for the guys in mission control, but that's just my guess.
The calendar did make me think about what astronauts did during their downtime going to and coming home from the Moon, though. Because having read the transcripts from Apollo 8, 10, 11, 12, 13, and 14, there was a fair bit of downtime. Most of it was filled with experiments, navigation checks, general maintenance and housekeeping, and taking some of the most stunning pictures of the Earth and the Moon. In looking through some raw and restored 16mm footage, it seemed like there was also a good amount of shenanigans and shaving on those historic lunar missions.