Understanding how students’ prior knowledge affects their learning of new concepts is essential for effective teaching. The same learning activity, or the same explanation, may have very different effects on students with different prior knowledge.

In the context of teaching programming, prior knowledge includes the programming languages students studied in prior courses. In this experience report we describe our observations in teaching object-oriented programming in Java to students who previously learned functional programming in Racket’s student languages. We highlight four concrete situations we encountered in bridging between these two languages. We detected and addressed these situations primarily thanks to a teaching assistant who assisted in both of the courses. Based on our experience, we believe that such sharing of teaching staff across introductory programming courses can be greatly beneficial for student learning.