Saying out loud
I think when we say something loudly, for example, read a poem loudly while we also read it in our mind, there are more chances of us remembering it than if we were to just read it in our mind without any sound. This I think is because of the sounds. That is, we not only see the words in the book but also listen to the sounds. So there are two sets of inputs (visual and sounds) that goes to our brain and memory and thereby making it easier to remember.