Assalaamu alaykum wa rahamtullaahi wa barakaatuhu. Every morning, during the first period at school, a boy recites Quran and then says, "Bismillaahillazi la yadurru ma' Ismihi shay..." till the end of the supplication, three times, and the rest of the class repeats after him. Then he says, "A'udzu bikalimaatillaahittaammah...' till the end of the supplication, three times, and the rest of the class repeats after him. What is the reward of this practice? The method is that he says 'Bismillaahillazi' and then the others also say, Bismillaahillazi,' then he says, 'La yadurru ma' Ismihi shay' and then the others also say, 'La yadurru ma' Ismihi shay', and so on.

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

There is no harm in having the students repeat some supplications (Du'aa') collectively if the purpose is to teach them and help them memorize, as understood from the question. This action does not fall under religious innovations and they earn the reward for teaching and memorizing these supplications.

Shaykh ‘Abd Al-‘Azeez ibn Baaz was asked about the ruling on reciting the Quran and Thikr (expressions of remembrance of Allah) (collectively and) out loud. He replied:

"...Reciting Quran and Thikr collectively after Tasleem (end of the prayer) has no basis in the Shariah and is not part of the religion of Islam as far as we know. None of the Companions or the scholars who followed them did this. The only exception in this regard is teaching young children and training them to recite the Quran correctly with a good voice and observe the rules of Tajweed (rules governing pronunciation during recitation of the Quran); this may be excused at schools and Quran classes in order to teach and train them to read the Quran correctly, pronounce the words properly, recite it with a good voice, and help them listen to the correct recitation. However, it is not allowed for people to recite the Quran collectively as such at homes and mosques; such an act is not prescribed in Islam. Each person should recite individually to himself or recite it to others, who would listen to the recitation, rather than recite the Quran collectively. We know of no basis in the Shariah for reciting the Quran collectively as such, and the same applies to reciting Thikr." [Excerpted with slight modifications]

Allah knows best.