Learning efficiency of sitting in first rows of the lecture hall
This article(The Effect of Seat Location on Exam Grades and Student Perceptions in an Introductory Biology Class By Steven Kalinowski and Mark L. Taper) examined the seat location during lectures and its effects on exams. It details the results of some prior studies and their own.
They assigned seating in the following way;

On the first day of class, we randomly divided students into groups of
three, and assigned each group to a row. Two groups were assigned per
row—except for the front row, which we left empty (because we believed
some students might be uncomfortable sitting in the very front). We
did not tell the class that we were studying the effect of seat
location on their learning

They used exam scores to measure student learning during lectures. Five exams were given to the class: four midterms and a final.
Their main finding was that there was no effect of seat location on exam scores
in the class.
They report that they obtained two noteworthy results.

First, we found no evidence that grades or student attitudes were
affected by seat location ...
Our second noteworthy result was that students who chose to sit in the
front of the lecture hall on the first class had significantly higher
GPAs than students in the back (P = 0.009, R2 = 0.18) (Figure 2). The
slope of the regression line was –0.10, indicating that, on average,
GPAs decreased by 0.1 point (on a 4-point scale) per row. This
represents a substantial difference in GPA between students in the
front and back (the regression line dropped from 3.9 in the front of
the lecture hall to 2.7 in the back).