Tulsa Public Schools has issued an appeal to parents to make sure their children are in class.
The school district has completed the first week of school, but so far has more than 800 fewer students enrolled than the same time last year.
One reason for the lower numbers is the start of an elementary charter school with 280 former TPS students.
Tulsa Public School has been making automated phone calls to parents reminding them classes are underway and asking them to contact the school if there's any reason the child is not in class - including the lack of a school uniform.
TPS provides free uniforms to children who need them.
The telephone announcement cautions parents unless children are in class during the first week, the district "may have to cut teachers" leading to overcrowded classroom.
On the fourth day of school last year, Tulsa Public Schools had 39,319 students in attendance.
Last Thursday, TPS had 38,428 children in class — a loss of 880 students.
Tulsa Public Schools started August 20th and adjusts teacher placement after the fifth day of school. Administrators say typically another way of new students arrives after Labor Day, which is two weeks into the school year for 2012.