A Learnable-by-Design (LEAD) Model for Designing Experiments for Computer Science Labs

India graduates 1.5 million engineering students every year, majority of them from its Tier 2 and Tier 3 colleges where there is severe shortage of qualified faculty and lab infrastructure, and where English is second or third language for most students. To provide affordable virtual laboratories to these engineering colleges, Government of India runs the Virtual Labs project with a select set of participating institutions to create virtual labs required for entire engineering student population of India. The program suffers from two problems: 1) lack of focus on pedagogy and learnability of labs being created, and 2) little ability to scale to more teachers and subject matter experts to produce labs aligned to local contexts. This paper presents a model (LEAD model) for the design of virtual labs for a data structures and algorithms course in computer science and is intended to address the problems stated above. The model encodes the principles of learning in the design and structure of an experiment so that labs can be learnable by design. The model is based on constructivist theory of learning. It uses Bloom's Taxonomy for defining learning objectives and applies Merrill's first principles and Gagne's 9 events of instruction as instructional design methodologies. To ensure tasks in an experiment indeed aid learning, the model requires a mapping between tasks and learning principles to be created and published along with the experiment. The model uses a pedagogy that lays strong emphasis on conceptual understanding without the use of code or program. To demonstrate the efficacy of this model, we present the data analysis of the feedback from early users of one the experiments. Even though limited in scope, data shows that experiments built using LEAD model can aid understanding for the students.