Split Screen Safari

When in Safari in a class i am taking, i have a notebook in the class tab i write in, and then also in the same class I have to watch a video and take notes. I have tried to split the screen so I can watch the video and take notes at the same time, but it won’t let me switch out. I have just switched from a surface pro which could do this when using google chrome, and now I am on a IMac 27, and also an iPad Pro.

Any help to do this please, so i don’t have to use 2 devices?

Thank you

INDY