Changing pedagogy is a promising avenue for improving education in developing countries, especially when done without changing current inputs, such as teachers and instruction time. Previous research suggests that tailoring instruction to each student needs can produce significant learning gains. In this paper, we present the results of a randomized evaluation of a program that uses an individualized approach to tailor instruction to each student to teach Mathematics to preschoolers in Peru. Our results show an improvement of overall Mathematics outcomes, which persist even one year after the program ended for some areas. We find no evidence of differential effects by gender, language-spoken at home, and proxies for socioeconomic status, in contrast with results from previous research that suggest Mathematics programs are biased along gender and socioeconomic lines but we do find persistent stronger impacts on students whose teachers have university degrees.