First welcome to PS !Sight reading can be interpreted in a couple of ways. One is that you read your practiced material vs playing it memorized. The one advantage to that obviously is the score is at hand. Sometimes we play half memorized but with the score up in front of us as reference.The more common way to interpret the term sight reading is that you play a piece cold. Never having seen or not having played it in a long time or as part of your memorized repertoire, you sit down and play it off the score first shot. I.E., a person brings a piece in to his teacher, or her teacher, shows it to them and the teacher sits down and plays it for them off the score they brought in.