Answer:
Yes, your sentence is gramatically CORRECT because the translation of the sentence is "my brother will go to school tomorrow". Not only this but this could also work: "Mi hermano podría ir a la escuela mañana." Which means "my brother could go to school tomorrow"
Explanation:
I hope this helps!
1:the nails
2:an audition
3:the auditions
4:the wedding
5:the date
6:the contest
7:a special event
8:exited
9:nervous
10:calm