There are many different reasons why children have problems paying attention. One child might be visually oversensitive and thereby distracted by bright sunlight coming in through a window or by too much color on a bulletin board. Another child, who is oversensitive to smells, might be distracted by the teacher's perfume or by the odor coming from a cage where animals are kept. Auditory sensitivity can be just as distracting. Some children are so sensitive to certain kinds of low-pitch sounds, such as motors, that if their classroom happens to be near the boiler room, a rumbling noise most people do not even notice will grab their attention. There are also children who are underreactive and may not respond to sounds or to touch. Dr. Greenspan explains that the mind has many different functions that contribute to attention. If teachers treat all intrusions on attention as one and the same thing, they will not be able to help children master their own particular challenges. By looking at inattention in terms of what contributes to it, rather than as one global function, teachers will be better able to identify the various origins of the problem in different children. If they can figure out the underlying troubles, they can develop specific exercises to strengthen the underlying functions.