An Interactive Tutorial for Learning to Manipulate References: (Abstract Only)

Understanding basic manipulation of object references is a conceptual prerequisite to understanding many data structures, beginning with linked lists and trees. Unfortunately, there is often a gap between introductory programming courses that introduce reference variables and creation of objects, and second-semester programming courses that immediately skip to introducing linked lists. As a consequence, students begin using references extensively during Data Structures and Algorithms courses without enough knowledge about how references work. To fill this gap, we created a tutorial about basic use of references and the manipulation of objects using references. The tutorial, implemented as part of the OpenDSA eTextbook system, focuses on learning through visualizations and interactive exercises. Students work a series of small code-writing exercises, inspired by the JhavePOP system. These exercises use simple program visualization to let students see the result of running their program. Manipulative exercises test student proficiency at reading and understanding small sections of code that use references to link objects. All exercises are automatically assessed, providing immediate feedback. Our evaluation of the tutorial's effectiveness will focus on identifying and correcting student misconceptions. Optional sections of the tutorial introduce the program stack and the dynamic memory heap.