Effectiveness of program visualization tools in teaching and learning programming is well documented. However most of program visualization tools are desktop applications, this study aims at investigating students' perception of program visualization on Android smartphones. Study result shows that program visualization using smartphones can arouse students' enthusiasm in learning programming especially when they can write program to interact with their environment. Students were interested in writing small programs to interact with smartphone sensors and perform trivial functions like sounding an alarm whenever a phone enters a school football pitch. [For the complete proceedings, see ED601100.]