The first part of this activity involves modifying an already-existing program, just as with the HTML tables at the beginning of the semester. In particular, students take a very simple page that has only one button (to add two numbers together), and modify it to make a "four-function calculator." The students experience and learn to deal with syntax and other errors, but almost all of them are able to complete this part on their own.
The second half of Phase III is more challenging. Students are required to generate a working program almost "from scratch". We begin with a general discussion of algorithms, in which we review all the games the students played earlier in the semester. We pay special attention to the level of specificity that will be required to communicate our intentions to the computer via a programming language -- any programming language!.