Attempting to divide people based on race or gender is called segregation, which causes rumors to start about the segregated groups from other groups. People who support segregation based on gender are not aware of the clear societal impacts that it will have on young minds. It's not good for children or society to be segregated.
Why does it matter if their in the same class. They're learning the same material so it doesn't really matter does it? See it's more of a hassle for the school to get more teachers when it really should be needed at all. Same material same class regardless of Gender