What can I do to stay focused when learning?

I think one of the examples from school is that one of the teachers asked why subject at school are mixed in hours? So sometimes you would have one hour of math, later you'll have let's say English and later history because different parts of brain work. And when you shift things together, one part of brain rests and another can work. So I was trying to use the same philosophy with my activities. It's about how we shuffle our time that you can do a lot, you can learn languages and you can learn other things. If you shuffle it, you will be more efficient.