Bad
dunce - A derogatory term used to ridicule someone who is not very clever, or who does not learn easily.
Being called the dunce of the class motivated Joe to work harder and he finished top of the class. Now sometimes he puts on a joker's costume to make fun of those who used to make fun of him.
impressionable - Easily influenced by somebody or something, usually due to being inexperienced or naïve.

Because children tend to be very impressionable, their use of the internet should be monitored, so that they are kept away form undesirble influences.