The teacher was recruited in March by the department from the SGB after the school's mathematics teacher went on maternity leave.
On Thursday, he allegedly hit pupils on their buttocks, apparently saying he was not going to tolerate pupils who perform under an 80% target.
A parent of a Grade 9 pupil said she was shocked after her daughter came home with a bloodstained school uniform.
"He stroked [hit] her on her buttocks until the sanitary pad shifted and she had to mess herself in front of the whole class because she was on her periods," the mother said.
The teacher's action was condemned by other angry parents who took to social media demanding his dismissal.
Gershwin Chuenyane, communication manager for the provincial department of education and sport development, confirmed the assault and the subsequent expulsion of the teacher.
He said the replacement for the mathematics teacher and that of the SGB member were being prioritised.
"Discipline problems in schools are fast becoming a common cause for expulsion and/or suspension whether the teacher is employed by SGBs or under the Employer's Education Act."