Introduction to Data Science (IDS) courses are being offered by many different departments either as a mandatory or an elective course. Because of the foundational nature of IDS courses to develop students’ understanding of data science, it is important to be aware of students’ potential learning difficulties. To that end, we conducted semi-structured interviews with 14 IDS instructors to study students’ difficulties. Qualitative content analysis was used to analyze the data. IDS instructors reported that students without prior coding experience encountered more syntactic difficulties than their peers. In terms of conceptual and strategic knowledge, students experienced difficulties in understanding principles of data visualization, the basics of coding, joining data sets, debugging and data wrangling. These findings suggest that IDS courses could be improved by addressing student difficulties and invite conducting future research with students to understand the dimensionality of student learning to improve capacity in data science (education).