Official websites use .gov A .gov website belongs to an official government organization in the United States. Secure .gov websites use HTTPS A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites. National Park Service Search Exiting nps.gov Rate the Lesson Plan Student Activities Geology, Relatives, and Time Grade Level: Middle School: Sixth Grade through Eighth Grade Subject: Science Using a simple three-or-four-generation family tree, students construct a relatives time tree that mimics the major divisions of