I work as a teacher in a Preschool and it is open on Chol Hamoed. Can I work on Chol Hamoed?
If keeping kids in preschool is saving Jewish children from other non Jewish influences, one may keep the school open and it is encouraged to do so, even having kids write etc.
As for the teachers, teaching involves no Melacha. Therefore, they may go to school and even receive payment for their work. Moreover, it’s L’tzorech Mitzvah, Tzorechi Rabbim as well as a Davar Haaved.
כן הכריעו אחרוני זמנינו – ראה הנסמן בס׳ חוה״מ כהלכתו ו, עה. ולענין קבלת שכר – ראה מג״א תקמד , יו״ד. וראה בס׳ הנ״ל ט, ב-ג ואילך