Interactive tutorial system for linear circuit analysis: Impact on learning and novel tutorials

The expansion and evaluation of a step-based tutoring system for linear circuit analysis is described. This system creates its own circuit problems (with variable topologies and element values) for students to solve, along with fully worked example solutions. New tutorial modules have been added, including waveform sketching and Laplace transforms (for a total of 17 released modules). The former involves the sketching of waveforms as a function of time in an interactive web-based interface, where students are required to find the voltage across an inductor when given its current (by differentiating), and other similar problems. The latter involves computation of direct and inverse Laplace transforms from randomly generated functions of various types, where students use an interactive template-based interface to enter their equations for checking. Other important capabilities have been added as well, such as voltage and current division equations, generation of circuit solutions using superposition, and generation of transient circuit problems involving switches. The waveform sketcher is further being adapted to permit sketching of Bode plots from system response functions, and vice versa. A large in-class evaluation was carried out in Fall 2015 with ∼70 students to compare the Circuit Tutor system to a widely used commercial publisher-based system. Students were randomly assigned to either use one system for node analysis homework, and the other system for mesh analysis homework, or vice versa. An in-class quiz then compared student performance. Students were also surveyed on their preferences. A large, statistically significant [t(64) = 3.09, p < 0.05] advantage was found for Circuit Tutor on node analysis of 0.72 standard deviations (average score of 72% for students who used Circuit Tutor, compared to 49% for those who used the publisher system). For mesh analysis, the Circuit Tutor average was 71% vs. 65% for the publisher system, but the difference was not statistically significant [t(64) = 0.88, p = 0.38]. The larger advantage of this system for node analysis may be due to the fundamentally easier nature of mesh analysis. In the survey, 86% preferred Circuit Tutor and 9% preferred the publisher system, and 94% felt that Circuit Tutor more effectively taught them the topic for which they used it, and 3% felt that the publisher system was more effective. The Circuit Tutor system has now been used by over 2300 students in 54 class sections at eight different colleges and universities, with generally very favorable ratings.