"Zoom In is a free web-based platform that helps students build literacy and historical thinking skills through "deep dives" into primary and secondary sources.
Choose from 18 content-rich US history units designed to supplement your regular instruction and help students practice skills required by the new, higher standards: reading documents closely and critically, identifying point of view and purpose, engaging in text-based discussions, and writing explanatory and argumentative essays grounded in evidence."
Documents via website have annotations. Documents, images, and audio can be searched by time period starting with the earliest of times. Site recommended by Turning Point Learning Center.