In our grade level we have an overarching theme that we're supposed to be exploring in all of our units: community. Now that's pretty broad and applicable to almost anything. After our first unit where we teach students what it means-- people living and working together-- and examples of human communities in America-- urban, rural, suburban-- the theme could be applied to anything kids wants to know. Communities of ocean animals ... and those species who are not communal animals. Space, and the international space station. The list goes on and on. Building real world knowledge and literacy skills in the process. The problem is teachers aren't taught to think this way in their prep programs and administrations want uniformity across the grade levels in most cases. So you get canned curriculums, basals, etc.