Stupid group of schoolchildren taking the wrong direction (5)
I believe the answer is:
crass
'stupid' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for crass that I've seen before include "Insensitively stupid" , "Coarse" , "Witless" , "Grossly insensitive" , "Grossly stupid, tactless" .)