Education is a distinct "sphere of justice" where resources and rewards (educational "goods") are being constantly distributed, and the fairness of their allocation is being evaluated, eliciting a sense of justice or injustice among the evaluators. A sense of (in)justice is a subjective perception of an individual that the reward s/he receives (actual reward) does not match the reward s/he thinks s/he deserves (just reward). This study investigates students' sense of (in)justice about grades in school, focusing on two questions: (a) What is the level (intensity) of sense of injustice in three subjects: language, mathematics, science (b) Are students' sense of (in)justice stratified by gender and SES, similar to the well known stratification of academic achievement? The study was carried out in Israel in conjunction with PISA international assessment in a national sample of 165 high schools among 4,500 15 year old students.