Uncovering heterogeneity in achievement during the Covid-19 pandemic: Math grades trajectories and their predictors in middle school

•Studies trajectories of math achievement in middle school students thru Covid-19 pandemic.•Uses archival data collected between 2020 and 2022 on 17,685 students nested in 460 schools.•Applies growth mixture modeling and identifies seven trajectories.•Reveals substantial heterogeneity unobserved in previous studies.•Examines the effect of student background characteristics on trajectory group membership.