To seat the students as one pair and three singles means many more possible arrangements, as it needs to be SS-X-S-X-S-X-S-X-, where X is not a student.
Available to fill the four non-student positions are three teachers, so at least one of the teachers must be sub-divided. Now, a single teacher could be halved but halving vertically (into a left and right half) would be different from halving horizontally into a top and bottom half, two consider just two directions. Then the spacing objects need not be equally sized, so we could use just a fraction of a teacher (say, a leg) for the fourth position... but is a left leg identical to a right leg, or are these yet more possibilities needing to be accounted for? And, do we have to triple the options as deconstructing one teacher is different from another? Perhaps one of the students will volunteer a school bag as a separator and spare the teachers from subdivision... but then, if that student is adjacent to their own bag, does it return to being a single unit, and so the bag only acts as a separator when not adjacent to its owner?
The possibilities under this interpretation are endless... I think the wording needs to be considered as restricting student groupings to a maximum size of two without limiting the number of such groupings.