Developing fluency across symbolic-, macroscopic-, and particulate-level representations is central to learning chemistry. Within the chemistry education community, animations and simulations that support multi-representational fluency are considered critical. With advances in the accessibility and sophistication of technology, "interactive" computer simulations are emerging as uniquely powerful tools to support chemistry learning. In this article, we present examples and resources to support successful implementation of PhET interactive simulations. The PhET Interactive Simulations project at the University of Colorado Boulder has developed over 30 interactive simulations for teaching and learning chemistry. PhET simulations provide dynamic access to multiple representations, make the invisible visible, scaffold inquiry, and allow for safe and quick access to multiple trials, while being engaging and fun for students and teachers. The simulations are readily accessible online, and are designed to be flexible tools to support a wide-range of implementation styles and teaching environments. Here, we introduce the PhET project, including the project's goals and design principles. We then highlight two simulations for chemistry, Molecule Polarity and Beer's Law Lab. Finally, we share examples (with resources) of the variety of ways PhET simulations can be used to teach chemistry--in lecture, laboratory, and homework.