It is essential for educators to identify the student's reading ability when learning debugging strategies. Forty-five senior high school students (average 17.6 years old, SD=0.35) participated in this study. The participants were divided into three groups to examine the effect of three teaching materials including 1) normal reasoning, 2) a debugging process model, and 3) a debugging process model and three debugging strategies, namely, forward strategy, backward strategy, and CLOCK-based strategy. While the participants debugging a digital circuit question, the eye tracker recorded the eye movement data for analysis. The results indicated that participants receiving a debugging process model and three debugging strategies improved their debugging skills significantly by: 1) increased percentage of the participants finding bugs correctly, 2) increased percentage of the participants using debugging strategies correctly, and 3) reduced time spent on debugging in average. The findings may help educators and researchers understand the benefit of debugging strategies on digital circuits to design better teaching materials, methods, and learning strategies.