Computer Science instructors have been exploiting learning technology such as Algorithm Visualization (AV) for last few years to explain hard-to-understand algorithms to the learners through simulations and animations. In this work, we explore an active and highly engaging approach, namely, the construction of visualizations of the algorithms under study. Our approach is further augmented with automated assessment of students' inclass construction activities, which they execute as apps in their mobile devices. In this paper, we utilize case study, a step-by-step visualization of a construction exercise app, to explain how technology is leveraged to provide a richer way for learners to interact with a problem, and how instructor can acquire real-time evidence of learners' comprehension of covered lecture material. Our experimental evaluation shows the educational benefits of the proposed approach in terms of enhanced student learning, reduced drop-out rate and increased student satisfaction.