The word "Art" is a useful, succinct, little word that trips off the tongue and doesn't seem to have any useful alternatives. Using the word "Art" indiscriminately, however, can get in the way of understanding. Art is typically defined as the expression of human creative imagination, typically in visual forms such as painting or sculpture, to be appreciated primarily for their beauty or emotional power. We expect too much when we conflate Art with Design, which is the process by which concepts for useful new products, buildings, machines, etc. are developed.
To make matters more confusing, there are two other phenomena that we are uncomfortable referring to as either Art or Design. These outliers usually fall in the domains of Visual Culture or Visual Communication. Garden gnomes, carved pumpkins and other crafts, for example, are examples of traditional, typically anonymous, visual forms like folk arts and crafts usually created by untrained people, that fall into the category of Visual Culture. Visual Communication, in turn, includes even more prosaic forms like maps, charts, diagrams, I.D. photos, and X-rays that we usually don't consider to be Art, Design. or Visual Culture.
I argue that we serve interdisciplinary learning better by embracing this more encompassing view of our visual world than is encapsulated in the word "Art". Focusing on "Visual" rather than "Art" helps us see that scientific illustrations, graphs, maps, and other visual artifacts that are neither Art, Design or Visual Culture but Visual Communication, and help students see, think, understand and communicate information and ideas visually. To say they are all "Art" is convenient but diminishes our understanding of what we typically mean by the word and dishonors the value of the others. Some Designers feel that calling them Artists doesn't acknowledge the unique value of their professions.
It is not so much the Arts that we want to integrate into learning but our visual (not just art), auditory (not just music) and haptic (not just dance) modes of learning.