PhET is a free resource that has been popular with science and math teachers for many years. PhET provides free interactive math and science simulations covering topics in physics, chemistry, biology, earth science, and mathematics. In the PhET library you'll find simulations appropriate for elementary, middle, high school, and university students. PhET even offers a search tool that will help you find lesson ideas built upon the free simulations.
56 of the PhET simulations are available to insert into PowerPoint presentations through the use of PhET's free PowerPoint Add-in. With the Add-in installed you can browse the available simulations and insert them into your slides. The simulations work in your slide just as they do on the PhET website.
Applications for Education
The PhET PowerPoint Add-in could be time-saver if you are planning to use more than one simulation during a lesson. Rather than clicking through menus or clicking through bookmarks to bring-up the right simulation, you could just create a slideshow that has your PhET simulations arranged in the sequence you plan to use them during your lesson.