PhET Interactive Simulations ( https://phet.colorado.edu/ ), a project of the University of Colorado Boulder, provides fun, free, interactive, research-based science and mathematics simulations for use across, primary, secondary, and higher education levels. We extensively test and evaluate each simulation to ensure educational effectiveness. All simulations are open source and free to all students and teachers. In this course, you will learn how to effectively design and implement a Teacher Guide that makes use of PhET鈥檚 simulations for mathematics and science. To finish this course, you need to complete two assignments with Peer Review: 1) Design a Teacher Guide that integrates an inquiry-based activity with simulations, and 2) Implement your lesson in your class, and reflect on the results. This course is the fourth and final of four courses that make up the specialization 鈥淎ctive Learning in STEM with PhET Interactive Simulations鈥. This course is also available in Spanish as 鈥淚mplementaci贸n de Actividades PhET para la Educaci贸n STEM鈥 and in Portuguese as "Implementa莽茫o de Atividades PhET para Educa莽茫o STEM".