The type of degree needed to become a teacher varies on what one will actually teach. Typically a public school teacher is required to obtain a bachelor's degree, along with the state's specific licensing.
Elementary school teachers typically obtain a bachelor's degree in general education. Middle and high school level teachers are likely to obtain a degree that is specific to the topic that will be taught.
In addition to a bachelor's degree, potential teachers are required to partake in supervised field experiences. This includes student teaching, which is practicing the method of teaching under the supervision of an already licensed teacher.