Some education systems have both quality and equality. They have achieved educational equity. This study aimed to uncover the practical wisdom of such systems in developing educational equality. A quantitative research design was used. Family capital and science achievement were the variables analyzed. They were secondary data collected by the 2018 PISA test. PISA surveyed students' family capital with questionnaires and measured students' science achievement with cognitive items. Six education systems with quality but low equality comprised the control group. Its sample size ranged from 4656 to 8312. The experiment group included nine quality and equal education systems, with sample sizes ranging from 3766 to 21490. The relative error and conditional probability were calculated to determine educational equality. Rawls' difference principle was used as a theoretical perspective. The findings showed that quality and equal education systems had three types: equal-start, equal-improvement, and egalitarian. The primary measure to improve equality in education is to ensure educational benefits for students in the bottom quartile of family capital. The development of educational equality was accompanied by a sustained reduction in the achievement gap between the disadvantaged and the advantaged. Implications for educational practice are discussed.