Better understanding

Hello guys I could`not saw the videos from the page that Sabrina give us but..I found the same ones in youtube.
This is what I saw http://www.youtube.com/watch?v=6hzrPNULYYQ a very interesting video. It`s a about a teacher who tries to make a difference while she is speaking, she asked to the children why she spoke faster or slow, the children`s answered suprised me, they know what the difficult to understad is if the teacher speaks in other way that children are not used to hear, or another posbility is the tone, if she spoke more exciting or not.
That called my atention because in our laboral experience generaly when we speak with children we use differents kind tones to speak to them, or expresions that represent more fun or better understanding.
I think when our speech is clear children pay attention, but what about if our speech is clear and at the same time we used expressions to show interest and fun, that would make them feel a connexion with us.
See you in class !