Several research studies have shown the benefits of code tracing to promote student understanding of program behavior. While code tracing on specific input values is a useful starting point, students ultimately need to be able to reason rigorously and logically about the correctness of their code on all (i.e., arbitrary) inputs. Otherwise, they may make false generalizations and may achieve only a shallow understanding. Results of a multi-semester experiment to answer the following research questions: (1) With or without steps, can students learn the basics of tracing code on symbolic input values using an online tool? And how important is classroom instruction? (2) What is the impact of motivation on student attitudes in learning to reason with such a tool? Data was obtained from 297 subjects who used the online reasoning tool in a second-year software development course for CS majors. Analysis indicates that students can do symbolic reasoning to trace code and that instruction and motivation have significant impact.