Free (Federal Resources for Educational Excellence) is a website full of hundred materials that can be used for teaching. The website does not provide lesson plans per se, but it does offer a lot of ideas about lessons and the materials to support them. The materials are categorized by subject matter although they are not categorized by grade level.
Applications for Educators
Many of the materials provided on Free are primary sources. Primary resources are a good material to use when teaching analysis skills. Some of the external links off of Free do link to lesson plans relevant to using primary sources.