**4. Classroom context of early childhood temperament**

Children's temperament has been related to their academic outcomes [6, 42] social success [43–45], and mental health [46]. Both reactive and regulatory temperament characteristics are salient to the classroom environment; reactive temperament traits, such as shyness [47], activity level [48], negative emotionality, anger [49], and regulatory temperament traits, such as attentional focusing and inhibitory control [48] are particularly relevant to children's success in school because of the inherently social, competitive, and academic nature of the classroom context. Children are expected to interact positively with peers by sharing and taking turns in group activities, as well as with teachers, by following directions and responding well to new information, changing circumstances, and redirection. These behaviors require children to enact behaviors that may be challenging (i.e., staying quiet, remaining still, raising a hand to get the teacher's attention, and waiting for a turn to participate in a desirable activity). For children with temperament indicative of higher reactivity, adjustment to the classroom environment requires them to engage higher levels of regulation. However, without sufficient regulation skills, this may be especially difficult. Thus, children with high reactivity and low self-regulation will likely have a more difficult adjustment to the classroom environment; a child with high self-regulation and, especially, low reactivity will likely have an easier adjustment. A visual representation of how low or high regulation and reactivity interactions affect a child's behavior can be found in **Figure 1**.
