Slide rule for a good night's sleep

http://www.unisa.edu.au/news/2007/190707.asp

Researchers at the University of South Australia have found that a general lack of awareness about the amount of sleep that children need at different ages is a contributing factor to sleep loss. As part of a broader public health strategy addressing sleep, health and learning in children, they have developed the Sleep Slide Rule for use in the classroom to illustrate the relationship between children's age and their sleep needs.