孩子的Algebra teacher 是个代课老师

The first one was an Indian lady, who just got her teaching credential.  He complained that lady was not familiar with the textbook.  This week, the Indian lady is gone, the new substitute teacher is even worse.  Students are not learning anything.  According to what we were told the original math teacher won't be back until late October. 

How can parents do in the mean time?  Complain to school?