Estan because its speaking in 3rd person and about the students, so esta'n
Yo- iba
Tu- ibas
El/ Ella/ Usted- iba
Nosotros- íbamos
Vosotro- ibais
Ellos/ Ellas/ Ustedes- iban
Hope this helped!
Answer by Mimiwhatsup: Students take pencil sharpener and ruler to school.
This is true it is grammatically correct.
The answer is abras
hope that helps, God bless!