The Library of Congress has a range of great blogs looking at collection highlights and how to use primary sources in the classroom.
Some recent posts of interest from the education blog include:
What makes a primary source a primary source?
Looking harder: inspiring close observation
Selecting questions to increase student engagement
For similar posts, take a look at the Teaching strategies page. Their Teachers’ section also has useful templates and lesson ideas to help students engage with primary and secondary source material.
The Library of Congress also has a photographic collection blog, legal collection blog and a science, business and technology blog.