In some subject areas, topics build on one another in a hierarchical fashion, so that a learner must almost certainly master one topic before moving to the next. For example, an elementary school student should probably master principles of addition before moving to multiplication, because multiplication is an extension of addition. Similarly, a medical student must have expertise in human anatomy before studying surgical techniques: It’s difficult to perform an appendectomy if you can’t find the appendix. Vertical transfer refers to such situations: A learner acquires new knowledge or skills by building on more basic information and procedures. In other cases, knowledge of one topic may affect learning a second topic even though the first isn’t a necessary condition for the second. Knowledge of French isn’t essential for learning Spanish, yet knowing French can help with Spanish because many words are similar in the two languages. When knowledge of the first topic is helpful but not essential to learning the second one, lateral transfer is occurring.
* appendectomy: 맹장 수술