Icebreaker activities are perhaps some of the most well-known gamified activities teachers use in their classroom. They are usually short activities that are particularly useful at the beginning of the school year or when a new class, group or course comes together. They can also be used again when a new student joins an existing group. Icebreakers generally involve some form of interaction or collaboration between students.
Icebreakers can not only be used to get to know (new) people but can also be adapted to introduce new topics and contents (see for example: 2 Truths and 1 Lie).
It can be particularly challenging to "break the ice" in the context of an online teaching environment - but there's always possibilities (see GarticPhone or Online Workshop Icebreaker).