Health in accordance with what the WHO is a State of physical, mental, and social well-being and not merely the absence of disease or weakness (WHO).While in Charter Ottawa said, that health is a resource for everyday life, not the objective of living. Health is a positive concept emphasizing the resources of the personal, social and physical abilities (Ottawa Charter) , that also means that health it is the most important point in the lives of many people who do not understand the meaning of health itself up to let her self-fall ill due to his strenuous, so are the students and the students now have a very busy school schedule
In the area of banyumanik there are 8 High school (SMA), from 8 school 2 of them is a public school that is SMA negeri 4 semarang and SMA negeri 9 semarang. The rest is private school that is SMA Mardisiswa Semarang ,SMAi Al Azhar 14 semarang, SMA nasional , SMAi Hidayatullah ,SMA Multazam ,SMA Bina bangsa. The school is certainly have the infirmary room(Unit Kesehatan Sekolah) because it has stated Since the year 1976 and reinforced in year 1984 with the publication of the “SKB” Minister of education and culture, Minister of religious affairs, the Minister of health, and Minister of Home Affairs who updated the year 2003 which said that the Infirmary as one program that directly relates to learners (Hariyani, 2016, )
Infirmary is the way school to improve the quality of education and learning achievement of learners by improving the behavior of clean and healthy life and health status of learners and school citizens as well as create a healthy environment, thus allowing growth and development of the harmonious and optimal in the context of the formation of Indonesian student but, the Infirmary itself doesn’t have facilities such as experts who are ready to check out students who are feeling unwell, the teachers usually checked by way of asking what was felt by students who are ill, but this method is not safe to done, because it was feared that the existence of a wrong diagnosis that can cause the wrong drug to students
To facilitate the diagnosis process required a decision support system, DSS (Decision System Support) is an interactive, flexible, and adaptable computer-based coupled with a comprehensive database and the decision maker own insight leading to specific, implementable decisions in solving the problem that would not be amenable to management science models. Thus, A DSS support decision making and increase effectiveness (Janakiraman V.S & Sarukesi.K, November.2006). .
The ID3 algorithm is an algorithm used to construct a decision tree, It uses the hierarchical structure for supervised learning. The process of decision tree starting from the root nodes to leaf nodes is performed recursively. Where any branching stating a condition that must be met and at each end of a class declares tree data, The method to be used in this thesis is the method ID3 (Iterative Dichomotizer)