How is music like Math Science Reading and Social Studies?

That depends on how deeply you study music. Basic music classes for elementary and high school students focus on learning to read music and play instruments. For younger students the constant practice of symbol recognition improves the quality of their normal reading speed and comprehension. Several studies that have been conducted proving that students who study music have a higher cognitive ability on average than those who do not. It is believed that studying music improves some of the skills, knowledge, evaluative insights, and therefore the cognitive capacities of these students.

Once students reach a higher level (I can attest to this from personal experience) advanced music theory classes involve the study of sound down to its composition. This means studying vibrations and sound waves, and learning to calculate the conditions needed to create them. At that point students are likely to learn many basics about waves in general as well as the physical science properties that effect them, things that will reappear in math and science classes. (emphasis on Algebra/Trigonometry and Physics)