Research shows that most of the experience and knowledge that students acquire in biology teaching have no real meaning for their real lives. Therefore, the topic of this unit is focused on sound fluid intake, which concerns every individual any day. This should increase the students' interest. The unit is further complemented by the role of dealing with the structure and function of artificial kidney in an effort to raise awareness among students about the problems of global growth in hidden nephrological diseases and the need for their early diagnosis.

The biological content in the unit is primarily related to the excretory system, circulatory system and digestive system. Actually, the unit may include all organ systems in which there is some form of water. The unit also offers the activities that require knowledge of chemistry, such as contents of organic or inorganic substances in beverages, pH, and osmotic phenomena in the cell. Further, knowledge of physics, mathematics and geography is also important.