Abstract Objectives This study examined children’s perspectives about returning to in-person school following lockdown due to the pandemic and about mask-wearing in class, as well as the mental health of children and parents during the pandemic. Methods This cross-sectional study was part of a 2-day school simulation exercise that randomized students to different masking recommendations. Parent-report of mental health and post-simulation child-report of COVID-19-related anxiety and mask-wearing were analyzed using descriptive and multiple regression analyses. Semi-structured focus groups were conducted with older students to supplement questionnaire data. Results Of 190 students in this study, 31% were in grade 4 or lower 95% looked forward to returning to in-person school. Greater child anxiety about COVID-19 was predicted by increased parent/caregiver anxiety (β=0.67; P<0.001), and lower parental educational attainment (β=1.86; P<0.002). Older students were more likely than younger students to report that mask-wearing interfered with their abilities to interact with peers (χ2(1)=31.16; P<0.001) and understand the teacher (χ2(1)=13.97; P<0.001). Students in the group that did not require masks were more likely than students in the masking group to report worries about contracting COVID-19 at school (χ2(1)=10.07; P<0.05), and anticipated difficulty wearing a mask (χ2(1)=18.95; P<0.001). Conclusions For children anxious about COVID-19, parental anxiety and education about COVID-19 may be targets for intervention. Future research should examine the impact of prolonged implementation of public health mitigation strategies in school on academic achievement and children’s mental health.