Economic views held by the general public tend to differ significantly from those of economic experts. To what extent would these differences fade away if people were exposed to economic instruction? In this paper we identify first-year college students’ initial preconceptions about economic issues, explore some cognitive biases behind them, verify their persistence, and test whether beliefs are correlated to course performance. We conduct a survey at the beginning and the end of the semester on a sample of students taking an economic principles course. We find evidence of preconception persistence, inconsistencies and self-serving bias. Most students do not incorporate the newly learned tools into their thinking process, even if they perform well. Many economics senior students have some beliefs that are contradicted in a principles course. Instruction in economics could be more efficient if it explicitly addressed students’ preconceptions and biases, a path already taken in other disciplines.