What are the benefits of being in a physical classroom compared to an online class when learning subjects like math or science?

In a proper classroom, there is far more interaction.

So, if I'm teaching you a concept, I can explain it to you, and if you don't understand, I draw it on the whiteboard. Still don't understand? I’ll sit with pencil and paper and show it to you.

You can interrupt me and ask questions immediately. I can correct small mistakes instantly.

Science in particular requires experiments to be done. While you can watch a video of it, seeing it live is far more memorable. Want to know what H2S smells like? How friction causes things to get hot? How KMnO4 is REALLY good at staining your hands? etc. And all the associated questions the ss ask.

It would be a bit like trying to become a certified pilot using nothing but flight simulators.

In my opinion, teaching online should only be done as a last option.