Translation:On Saturday the biology lesson starts at eleven.
It's pretty common in Asia and Eastern Europe, maybe other places as well. It's usually more of a half day. As for why... probably because Saturdays are work days for adults too. The 5 day work week seems to be gaining ground though.
Students had to go to school on Saturdays in Sweden too, but that was later abolished. It was always test day, my father have said. Even then, it was only really half a school day, since they were allowed home after lunch.
(Magne Ludvigsen) I think it is in the present because the biology classes on Saturday won't start only once at this time. (Maybe, since now, all the weeks it will start at this time).
Yes, I think so. Although, the use of the simple future in English tends to imply more certainty than using the simple present.