Arts Integration works for several reasons:

Howard Gardner's Theory of Multiple Intelligences basically states that there are several different ways that people learn best. Bodily/kinesthetics learn best through moving their body and objects. Visual/spatials learn best through creating visual representations of the subject. Naturalistic learners thrive in situations where they are immersed in real scenarios. Garder says that there are 6 more types of learners: musical, logical/mathmatical, verbal/linguistic, intra-personal, inter-personal, and spiritualistic.

Arts Integrated lessons that are well-planned and executed cover all of these intelligences allowing students who excel at one but struggle with the others to still understand the subject.