What makes study hard? – theory

AWhat makes study hard? – theory  One of the reason for students’ suffering life in school is theory.Theory is reasonable explanation on observed phenomena.   Even if they are reasonable, no theory is 100% correct.  Every theory changes and evolves to give a birth to new one.   Some of them are even selected to be discarded.  Theory can be changed next day but students learn, understand and memorize them as if they are the facts.   And students are even evaluated for the accuracy of the theory.  While theory evolves, students learn to stick with old theory.  They never learn how to change the theories.  This is why study is so hard.