There are a lot of observations you can make on each simulation.

Great interactive tools for teaching science and math concepts. The simulations are engaging and visually intuitive, allowing students to explore concepts like energy conservation, chemical reactions, and algebra through hands-on virtual experimentation. The academic value is outstanding, as it offers deep conceptual learning opportunities aligned with curriculum standards. While the entertainment factor is moderate, the interactive and exploratory nature of the tool keeps students curious and engaged.

I love Phet for many reasons, but my main reason would be seeing how gloomy my teenage students look when they first step into the classroom, and then seeing their faces light up when they look up at the smart board and see that the daily agenda says "PHET SIMULATION LAB TODAY". It's fun, engaging and ever since I began using Phet, the overall GPA of my students has increased and put our school in a much higher rating.

I love how open-ended each simulation is. It might be annoying sometimes because students could get distracted, but as long as I guide them with challenges for how to use the sim, they learn a lot. And sometimes they learn something unexpected! I only wish they had more simulations on more topics.