“…We focused our analysis on the first 12 minutes of the lesson, because the lesson start is at the same time very important and very demanding regarding teacher-student interaction (Pennings et al, 2017;Van Tartwijk, Brekelmans, Wubbels, Fisher, & Fraser, 1998). First, we examined univariate characteristics of the heart rate, Agency, and Communion time series: a) linear, quadratic, and cubic trend models, which indicate whether teacher's heart rate (or Agency, or Communion) in-or decreased continuously during the lesson and whether it de-or accelerated at some points, b) autocorrelation, which indicates to what extent heart rate values carry over to the next moment in time (i.e., temporal dependency), and c) stability, which combines the temporal dependency with the amplitude of heart rate changes.…”