Well, it has all the days on the week on it except for sunday. I am guessing that the kids were in school all these days. It is also arranged a little weirdly -- from left to right are the days in that month that are that day of the week. For example, in Ÿíâàðü -- January, the ?? means ponedel'nik, or monday. Mondays are on the 6th, 13th, 20th, and 27th. Anyway, that is what I expect it is.
Edit: Elec -- God would not have been an issue in Ukraine SSR -- there is a reason that we called them godless commie bas**rds right? (Note, this is totally a joke -- I love the Ukraine, but nevertheless, the point was true, there was no place for religious calenders in Communist Ukraine...)