MANKATO-September 4, 2012-(KMKO)-Schools are in session again, and that means drivers are asked to be cautious. With the start of school, posted speed limits near grounds will be enforced at 20 mph.  Drivers need to be cautious when passing buses, too. When a school bus arm is down and red lights are flashing, it is illegal to pass the bus from either direction.  Drivers who do so can be fined $300. Students are also advised to pay attention, listen and look both ways when crossing a street or stepping off a bus.