estúpido / estúpida (for a person, but this would be rude)
tonto / tonta (fool or foolish) is similar as is mudo (dumb).
"Estúpido" and "mudo" can mean stupid, but calling someone one of these words can be considered extremely offensive, as they may imply that someone has a mental or neurological disorder.
"No inteligente" (unintelligent) would be much more appropriate, though still possibly offensive.
You would say 'Clase de Espanol es muy stupido.'
En verdad, ¿eres estúpido?
Mexican is actually spanish. And it is estupido/a
its : MI clase española es muy organizada
Voy a empezar las clases..... is how you say i will begin class in spanish
'Clase de tenis' is tennis class in Spanish.
Yo aprendo mucho en la clase
Clase.
la gente es estupida
to say how well you are doing in a class (example below): i am doing good in my spanish class - hago bueno en mi clase española
La clase de Español es muy divertido con Sra. Agustin.
En el salón hay (The class where I am)
Esta clase
la clase