The main objective of this study was to determine the effect of discovery learning assisted e-learning in improving mastery of the concept of solution and solution concentration. The research subjects consisted of 19 dressmaking students, Al Munawwariyyah Vocational School, Bululawang, Malang. The results showed that discovery learning assisted e-learning can significantly improve student mastery of concepts with an N-gain average value of 0.63 (high medium) and an effect size value of 0,72 (high medium). Students' skills in applying the theory of solution and the concentration of a solution in the process of coloring cloth with a certain concentration increased. Through the activities of e-learning based discussion forums in the classroom, most students are interested in utilizing the fabric coloring theory in increasing fabric color variations to increase the attractiveness of the products produced.