## Article
### Flexibility: Flanker Task  
The repeated-measures ANOVA on accuracy (mixed congruent CR vs. mixed incongruent CR) by class, sex, and AM reveals the significant main effects of the congruent/incongruent condition (F\({}_{1,1066}\) = 1367.30, \(p\) < 0.001, \(\eta^{2}\)\({}_{\rm P}\) = 0.56), class (F\({}_{7,1066}\) = 31.73, \(p\) < 0.001, \(\eta^{2}\)\({}_{\rm P}\) = 0.17), and AM (F\({}_{1,1066}\) = 5.93, \(p\) = 0.015, \(\eta^{2}\)\({}_{\rm P}\) = 0.01). The interaction between condition and class was significant (F\({}_{7,1066}\) = 15.64, \(p\) < 0.001, \(\eta^{2}\)\({}_{\rm P}\) = 0.09). Post hoc analyses confirm that the accuracy is higher for the congruent than the incongruent trials at all class levels (all ps < 0.001). Congruent trials accuracy in the first four classes is lower than in the last ones; incongruent trials accuracy in the first classes differs from that of the intermediate classes, which in turn is lower than the accuracy in the last classes (Table 1; Figure S4a). The interaction between the condition and AM (F\({}_{1,1066}\) = 9.93, \(p\) = 0.002, \(\eta^{2}\)\({}_{\rm P}\) = 0.01) is significant, which demonstrates that accuracy scores are lower in incongruent than congruent trials (all ps < 0.001) and that incongruent trials are less accurate in the remote condition (\(p\) = 0.002). The triple interaction condition X class X AM is also significant (F\({}_{7,1066}\) = 2.21, \(p\) = 0.031, \(\eta^{2}\)\({}_{\rm P}\) = 0.01), but it is important to note that none of the scores in the in-person condition differ from the corresponding remote score. This interaction shows a significant congruent-incongruent effect for all classes in both assessment conditions. In the case of congruent trials in the in-person condition, there are the following significant differences between classes: 1 < 8; 3 < 5, 7-8; and 4 < 8. In the case of congruent trials in the remote condition, there are the following significant differences between classes: 1 < 7-8; 2 < 5-8; and 3-4 < 8. In the incongruent trials in-person, there are the following significant differences between classes: 2 < 7-8; 3 < 5-8; and 4 < 6-8 (Table S2). The variability ranges between 0.04 and 0.13, and between 0.16 and 0.31 for congruent and incongruent correct responses, respectively, showing a decreasing trend with age for both (Table 1).  
The repeated-measures ANOVA on RT (mixed congruent RT and mixed incongruent RT) by class, sex, and AM reveals the significant main effects of the congruent/incongruent condition (F\({}_{1,1077}\) = 1139.86, \(p\) < 0.001, \(\eta^{2}\)\({}_{\rm P}\) = 0.51), class (F\({}_{7,1077}\) = 12.01, \(p\) < 0.001, \(\eta^{2}\)\({}_{\rm P}\) = 0.07), and sex (F\({}_{1,1077}\) = 13.86, \(p\) < 0.001, \(\eta^{2}\)\({}_{\rm P}\) = 0.01). The interaction between congruent/incongruent condition and class is also significant (F\({}_{7,1077}\) = 2.22, \(p\) = 0.031, \(\eta^{2}\)\({}_{\rm P}\) = 0.01). Post hoc analyses confirm that the congruent trials are faster than the incongruent trials at all class levels (all ps < 0.001). The RTs in congruent condition decrease gradually with the classes, with significant differences between the first four classes and class eight. The RTs in the incongruent condition also decrease with classes: classes 1 and 2 are different from class 8, classes 3 and 4 are different from classes 5 and 6, respectively, and class 5 is different from class 8 (ps < 0.05; Table 1; Figure S4b). The sex main effect shows that boys' responses are faster than the responses of girls (1090.57 ms vs. 1144.12 ms). The variability ranges between 0.13 and 0.18, and between 0.12 and 0.17, for congruent and incongruent RTs, respectively (Table 1).