What it is. Playful Physics is a free collection of interactive physics models, from measuring a length to quantum tunnelling and the geometry of curved space. Each one has a simulation you can drag and change, the equations that drive it updating live, the working shown step by step, and a short quiz. "Playful" means you can explore freely: nothing is graded, nothing is locked, and every model opens paused so you choose when things move. Who makes it. One person in Perth, Western Australia, building it with Claude, an AI model made by Anthropic. The site is free and has no ads. How the models are made and checked. Every model is written with Claude. Automated checks run every model at its default settings and at the limits of every control, looking for errors, broken equations and missing units. The newer models also go through several separate reviews before they are published: an AI physics checker reworks the numbers and reads every claim, a design review checks the layout on screen, and AI testers try each model as a high-school, undergraduate and postgraduate student would. That catches a lot, but it is not the same as review by a physics teacher or researcher, and no school, university or curriculum body has endorsed the site. If you find a mistake, please report it: there is a link on every model page, and every report is read. Where it fits. Use it alongside resources you already trust, such as PhET, Khan Academy or your textbook. Its aim is to go a little deeper and further, with the working shown. The worked problems were developed with the help of standard textbooks, credited on the Further reading page. The problems here are written in our own words and with our own numbers. Using it in class. You are welcome to use the models in teaching and to link to any page: every model has its own address. A formal licence for other kinds of reuse has not been chosen yet; ask through the feedback page if you want to do something else with them.