Critical-thinking, decision-making, and processing skills are essential in Chemistry and other STEM fields; however, few courses offer opportunities for students to practice these skills and receive feedback. We have developed a pedagogical method and a prototype online tool, code-named "Alchemy", that addresses this gap and helps students learn and practice expert-like thinking. This presentation will provide an overview of the Alchemy tool, summarize its development and implementation to date (including extensive student involvement), and highlight student feedback and ongoing pedagogical research. An instructor not involved in the original development of Alchemy will also discuss their adoption and experience with it. The presentation will conclude with future plans (e.g. learning analytics) and opportunities for other instructors to become involved in the project.