Teachers are considered important role models for the behavior of children during early childhood. The purposes of this study are to: (a) compare activity levels of preschool children in a structured physical education (PE) class taught by an active or less active teacher; (b) examine the interaction effect of gender, school size, and teacher activity levels on the activity levels of children. The participants were 248 preschool children (134 boys, 114 girls; mean age = 5.5 years) and teachers from 12 preschools in Hong Kong. Regular classroom teachers conducted a 30-min structured PE class, and the participants' physical activity (PA) levels were measured using pedometers. The recorded step counts of teachers were employed to classify whether children were in the classes taught by active or less active teachers. Factorial analysis of variance was used to examine differences in the pedometer-determined activity regarding gender and school size between the different types of classes. The results indicated that preschool children had higher PA levels in PE classes taught by more active teachers than in those taught by less active teachers (1712 versus 951 steps). Future studies could explore other teacher-related factors that might facilitate appropriate strategies to engage preschoolers in higher PA during PE classes. Copyright © 2019 The Author(s).