In philosophy, realism is the belief that reality lies outside of the human mind; it is the focus on things that can be observed as well as things that exist independently of what the human mind believes to be true. An example of realism in philosophy is that a tree will exist in nature whether a human is able to recognize the tree.
Realism has nearly nothing to do with the human mind, but has everything to do with the way the world functions outside of the mind. Realists believe in rational thought and will only perceive things the way that they are truly seen, without any type of interpretation. Aristotle is referred to as the father of realism because of his break off from the philosophical teachings of Plato.
When realism is being taught to students, it is mostly based around real facts and scientific methods that are known to be true. Students are expected to think scientifically and to use mathematical procedures to get the end result of their thinking. Realist students need to be able to gather criteria and reach a solution using methodical thinking through the criteria. Realism is focused around the use of mathematics and science.