How about "As crianças assistem à escola para aprender coisas." Sounds to me like more proper English than "go to school." But then, What I don't know would Fill a Book. :=}
why is "as coisas" wrong here?
Because coisas here is in general sense as you learn many things/subjects at school.
Why is "as criancas" not accepted?
Can I say, "As crianças vão até escola para aprender coisas"? :)
"As crianças vão até a escola....", it would sound a bit unusual, once "até a" means to reach a certain place.... but understandable ;)
is it possible to use por instead para here?
no.you have to use "para" to mean "to". If you use "pela" (por+a) it means "by the school"