Thousands of Iowa children are heading to school for the first time today and many thousands more are returning for the first day of the new school year. For Iowa motorists, it may mean traffic delays and the need to be patient and on “extra alert” for darting young pedestrians.Iowa City Police Sergeant Bill Campbell says the motorists aren’t the only ones who need to use their heads today — the kids, too, must stay alert or they could end up in the hospital instead of homeroom.Sergeant Campbell says there will be thousands of big yellow school buses hitting the routes across Iowa today for the first time, further clogging the already-crowded roadways.He warns motorists to watch their speed, especially when approaching school zones where the speed limits are often reduced to 20 miles an hour.