Tuesday or Thursday?

The children’s school started on a Wednesday after the summer break. They brought home their schedules, and at the morning of the second school day  I was checking out the beginning times of the day. One of the kids’ lessons started a bit later on that day. I carefully scrutinized the schedules and noticed that the other one’s day was also starting later, and did not wake him up at the normal time. When I at last woke him up, he said he was late. I double-checked the schedule, and he was right, on Thursdays the school started early. But on Tuesdays it started later – my brain had interpreted the second school day of the week as Tuesday although I well knew, that this week started on Wednesday…