The actual distance between each pair of classmates was calculated following the procedure
described in van den Berg and colleagues (2012). For each pair of classmates, we counted the number
of desks and aisles in front of or behind them (horizontally) and in between them (vertically). Using
these numbers, Euclidean distance was then computed (Fig. 1). For example, if Child A sat 5 seats and
2 aisles away from Child B (horizontally) and 4 seats and 1 aisle behind Child B, the distance between