Construction of learning system for novice programming learners

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1.For the system generating verbal and visual explanations of target programs(1)Expansion of our program understanding mechanismIn our previous work, we proposed a mechanism to understand a behavior of a program in the domain world of "greater and lessen". We have developed an extended method for another domain world "two dimensional space" that is used for some numerical analysis such as 'Newton method' or 'Simpson method'. We achieved it by using heuristic rules to specify correspondence between a variable and an attribute of an entity in the domain world.(2)Development of a method to generate both verbal and visual explanationsIn generating verbal explanations, the system only have to pay attention to entities changed by execution of statements. However in visual explanations, it has to present the whole image of the domain world including the not changing parts. Therefore, we have redesigned the explanation generating unit. Then we evaluate the educational effectiveness of our system by an examination. By comparing the learners using our system to ones not using it, we have confirmed the effectiveness of our system.2.For the system assisting teachers by semi-automatic evaluation of learners' programsOur semi-automatic evaluation unit compares a learner's program with a standard algorithm representation written by teacher. In our previous system, data structures are restricted to concrete ones such as arrays, structs, and so on. We have extended the algorithm representation in order to handle 7 kinds of abstract data structures such as stacks, trees, tables, and so on. Our system translates an operation handling an abstract data structure into operations handling concrete data structures by rules, and then it compares them with statements in learner's programs. We have evaluated the extending method by measuring the accuracy of semi-automatic evaluation and confirmed our method is effective.