The rationale for this study is the search for ways to optimize expenditures on secondary vocational education. Optimization activities should lead to the creation of high quality human capital in the society. The purpose of this study is to verify the view indicating that schools with fewer students achieve higher learning outcomes. Nine classes were selected from a group of all secondary technical schools in Poland (N = 1683). Each class consisted of twenty schools selected by the average annual number of graduates in 2013-2015. A univariate analysis ANOVA was then carried out. The dependent variables were educational added values for matriculation exams in Polish language, the humanities, mathematics and natural sciences. The quality predictor in this study was classes determined by the average number of graduates. The study has led to the conclusion that higher learning outcomes expressed by the average educational added value are achieved in schools with more students. The highest average learning outcomes were achieved in schools with the number of students ranging from 564 to 640. It has also been shown that the average educational added value increases with the number of students in school. It may be supposed that certain numbers of students in school should not be exceeded; however, due to the lack of schools with the number of students far exceeding those in schools covered in this study, it was not possible to determine the maximum number of students in secondary technical schools that would allow them to obtain the expected learning outcomes.