Watch a few short videos on the Labor movement with your students. Three videos are listed on this page: J.P. Morgan Battles Coal Miners in 1902, Andrew Carnegie and the Homestead Strike, and 1930s GM Sit Down Strike.
This lesson plan from PBS organizes students into groups and requires them to negotiate demands between management and workers. I think this is a potentially great way for students to learn about labor and unions, but they will need some background information first, and it will probably take more than one class period. If you devote the time to make this activity work, I think your students would enjoy it and learn from it.
For your students with special needs who have trouble understanding holidays, you can print out this social story ($2.00 for digital download), then laminate and bind the pages. The comments and reviews were all positive, and there are lots of other social stories also available for download.