Repeating what someone else says to you to demonstrate understanding is called

Yes, when you repeat what is said then it sticks in your mind.

Echo: to say the same words that the other person has said to make sure you have an understanding

If it's a smaller child or infant, place one on the middle of the chest and on the child's back. (if it is a bigger child with enough room for two, place one on the upper right/your left of the chest, and one on the lower left/your right) the pads should never touch each other.