All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Supplicating is permissible in principle, thus it is permissible to supplicate in congregation as long as this is not taken as a regular habit and the people who supplicate do not believe that it has any speciality or that it is an act from the Sunnah of the Prophet .
Imaam Ahmad was asked: "Is it dislikeable for people to gather and supplicate Allaah while raising their hands?" He replied: ''What I dislike for my Muslim brothers is to do that deliberately as a regular habit." Is-Haaq Ibn Rahawayh said the same thing.
Moreover, Ibn Taymiyyah said: "To gather in order to recite the Quran or mention Allaah or supplicate is something good as long as this is not taken as a supererogatory Sunnah or linked to an innovation."
However, if this is taken as a habit which people do regularly at a particular time, then it becomes an innovation in religion and it must be avoided.
It appears from the question that you are regularly doing this act at a particular time which makes it classified as a religious innovation.
Finally, we ask Allaah to enable the students to succeed and do what is better for them and their nation in this worldly life and the Hereafter.
Allaah Knows best.