Guidelines for Hafrashas Challah in a Group Setting

I’m a teacher and want to make challahs for Shabbos with my students. I’m planning to prepare a large batch of dough—about 4 kilos—and let each girl braid her own challah and place it on a baking tray. The challahs will then be baked in each girl’s home. May I separate challah with a Bracha? I’d really appreciate an answer, thank you so much!

Shalom uVracha

If the teacher—or someone else—separates for herself a full shiur challah, the hafrashah can be made with a bracha.
But if the dough is divided so that each portion is less than the required shiur, the hafrashah is done without a bracha.