Aristotle is credited with the development of realism. Realism is about viewing the world in terms of what a person experiences through their senses. This is almost the opposite of idealism and its focus on the mind. Realist focus on experiencing things through as you may have guessed, experiences. Experiments in many ways are really just experiences people have had that were conducted in a scientific manner.
Within education, realism can be seen through proponents of experimentalism which emphasizes students have various experiences as part of their education. These experiences can be something as simple as a field trip. Hands on activities in the classroom is another outgrowth of realist thinking. Science is above the liberal arts because of its engagement with the real world in a concrete manner. The goal of realism in education is to encourage active learning through engaging as many senses as possible. Through the avenues of the senses learning takes place.