Engineering professionals need to employ argumentative skills to support their decisions. This research presents the findings of an intervention that was designed and implemented at two universities in Colombia, South America, to help students enhance their written argumentative skills through essays on ethical dilemmas. Engineering professors included explanations based on modelled examples that showed adequate argumentation and provided feedback to students. This experience included a pre-test, post-test and a brief intervention based on problem-based learning (PBL). Results show that students improved in essay aspects such as the introduction, presenting and supporting a thesis, including evidence with proper references and the creation of a conclusion. Standardized national test results also support the benefits of this approach.