Have your students log into the game as usual

Have your students travel to the Tyto Academy, then go to the launchpad behind the academy building

Once the player character is inside of the spaceship, they should be prompted to go to their assigned Expedition

Progress is automatically saved each in-game day. The students can leave the Expedition by closing their window, or traveling back to the Academy map. They should be able to go back and continue their Expedition.