Effective singing

Yesterday we played a nice game with Orestis. He was sitting calmly on the cushions with me in front of him. I was singing a melody that i saw he liked. When i stopped, i told him: "If you want me to continue, look me in the eyes." Thus, everytime he looked at me i would sing. Whenever he looked elsewhere i would stop. Sometimes it would take a long time before he looked at me again so, in order to keep the interaction going, i would hum the melody softly. As soon as he glanced at me i would raise my voice again. He was giggling the whole time. He loved this procedure apparently