Currently, the educational trend of developing learners’ compentence has being paid attention to, researched and applied in many countries around the world, including Vietnam. One of the teaching methods that are being implemented to help develop learners’ abilities is the STEM education method. This article has applied the lesson design process towards STEM education in building and implementing a STEM lesson on the topic: “Herbal tea from King Orange peel”. Experimental results showed that STEM lessons not only helped develop competence of problem solving for students but also contributed to raising students’ awareness, taking advantage of King Orange peel by-products to process into valuable products. This result can be extended to many other topics in the high school Chemistry curriculum to develop competence of problem solving and create learning excitement for students.