Designing safer chemicals is an integral part of green chemistry that supports good health and well-being. The teaching of molecule design through relevant courses has important implications for the education of sustainable chemists. In these courses, training in toxicology and hazard assessment is essential for students to study benign chemical design that promotes social and environmental justices. However, toxicology training has been rarely included in the course of molecular design, and education of green molecular design at the postgraduate level has been less involved. In this study, we developed an online classroom for toxicology training as a new component of our chemical molecular design course. This class was designed to provide students with a toxicity perspective for viewing chemicals by integrating our three web-based tools. The average score of students' attitude evaluation toward the web-based class was 4.0/5.0, indicating that the toxicology class achieved the expected effects and provided a good experience for students to learn about designing safer chemicals. This work may facilitate the education of green molecular design and inspire students to seriously consider chemically toxic side effects.