Using the first wave of the Growing Up in Ireland Survey of nine year old children we examine whether a teacher's assessment of their pupil's academic ability is influenced by the weight status of the child and/or the child's mother. Multivariate regression analyses of the teacher's assessment, controlling for the child's actual test performance, their BMI, their mother's BMI, other socio-demographic and teacher characteristics were undertaken. The study highlighted that child BMI was not a significant determinant but that children whose mother was obese were more likely to be rated as below average in reading and in maths compared to those whose mother was leaner, after adjusting for their measured ability. The potential for mother's weight status to influence teachers' assessments of their children's perceived ability could have long term ramifications for educational outcomes and warrants further study. (C) 2017 Elsevier B.V. All rights reserved.