a small group of students who learn together (like peas in a pod), either for academic convenience or due to
special circumstances (such pandemic, specialized programs, or homeschooling)
From Merriam-Webster blog:
The origin of pod, referring to a group of marine mammals, isn't known, but in the 20th century it was adopted to refer to
small groups of students as well. In response to the COVID-
19 pandemic, this usage has seen an uptick, as educators consider new models for educating students remotely or in
small groups referred to as "pods."
Learning pods—also called "pandemic pods," micro-schools or nano-schools—are small groups of students (typically three to 10
children) who learn together outside the classroom but still in person. Some pods are hiring tutors to teach a child's school curriculum; some pods are sharing teaching duties among
parents. Other families are opting out of their kids' schools entirely and treating a pod like a home-schooling co-op with an agreed-upon curriculum.
— Dani Blum and Farah Miller, The New York Times, 18 Aug.
2020