Participants
The present study was conducted in Shenzhen, one of the leading cities in China where early childhood education (ECE) has been well developed. A convenience sample of three public preschools was selected from the same community, serving families of the same socioeconomic status. In the preschools, a stratified sample of two classes each of K1, K2 and K3, totaling 18 classes, and then a random sample of 15 children from each class participated in the study, comprising 90 children from K1 (M = 47.72, SD = 0.36), 90 from K2 (M = 59.72, SD = 0.39), and 90 from K3 (M = 70.87, SD = 0.44). In China, children typically begin preschool at around the age of 3 and transition to primary school between 6 and 7 (Xie & Li, 2019). The different grades represent different age groups, with children in K1 aged 3-4 years, K2 aged 4-5 years, and K3 aged 5-6 years. To facilitate multi-group comparisons across ages, we transformed the continuous numerical variable of age into the categorical variable of grade level. The sample included 154 (57%) boys and 116 (43%) girls. All lead teachers from the 18 classes were female, with an average teaching experience of 8.94 years (SD=6.09), ranging from 4 years to 27 years (see Table 1).
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