Abstract : The research refers “overcrowded class" as a Constraint to authentic learning of Mathematics in Katsina State Tertiary Institutions, Nigeria. Learning would never be effective in an overcrowded class, is a situation whereby teachers are not convenient to teach, also students are not convenient to learn. This would no doubt have serious negative effect on the teachers and students’ performance. It was against this background that this research was conducted. The research is survey in nature, Katsina State has five tertiary institutions, out of which three institutions were randomly selected for the research. From each of the three institutions, results of six Mathematics courses were randomly selected across the levels making a total of eighteen (18) independent results for the research. The objectives of the research were to determine the teacher to students ratios, investigate relationship between class size and students' performance, identify the negative consequences of overcrowded class on students’ performance and offer solutions for improvement. The research questions were examined and the major null hypothesis formulated was tested at 1% significance level using Pearson Product Moment Correlation (PPMC) statistic. Major findings of this research are, “teacher to students ratios in Mathematics classes in Katsina State tertiary institutions are far from ideal”, “there is significant negative relationship between class-size and students’ Mathematics performance in Katsina State tertiary institutions” and “there is significant negative impact of overcrowded class on students’ Mathematics performance in Katsina State tertiary institutions”. Finally, conclusions and recommendations were made.

Keyword : Authentic, Constraint, Controlling, Tertiary institutions, Katsina State.