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 access and share PhET simulations with your students, and explore the features that make PhET sims a powerful tool for science and mathematics teachers. You will also review strategies for how to use PhET in circumstances where you are presenting a simulation in front of the whole class using a projector, interactive whiteboard, or sharing your screen online. This course is the first one of the specialization “Active Learning in STEM with PhET Interactive Simulations”, that include 3 courses in total. To finish this course, you need to complete two assignments with Peer Review: 1) Selecting PhET sims, 2) Select a strategy for a Whole Class set-up, and design your first activity. This course is also available in Spanish as “Introducción a las Simulaciones PhET para la Educación STEM”