The difficulties in teaching and learning computer programming remain a pressing issue to this day. Several studies and tools have been developed over the years to tackle this challenge from many different points-of-view. One of the biggest tools an educator has to support him in a classroom is the progressive explanation of how a source code is constructed and what effects each of its parts has on the overall result. Attempts to translate this live-directed tool to an on-line experience is usually time-consuming and lacking in features. In order to tackle this concern, a tool to create piecewise source code writing demonstrations was developed - Stepwise Source. The main idea behind this application is to allow step-by-step explanation of a source code construction, along with any relevant annotations and automatically assessed challenges that an educator may add. By providing a dynamic platform for both students and lecturers, this software aims to improve the teaching and learning of computer programming, while trying to imitate the information flow of a live lecture, with the added benefit of student-directed pace of explanation. Through interactive guidance and automated assessment, this tool has the potential to foster a deeper understanding of computational principles and promote proficiency in programming skills.