What major events in the history of labor in the United States (or globally) would you teach to a class of union construction workers?

Hey everybody, I've been given the opportunity to teach a labor history class at my union hall. This will be the first labor history course that I have ever taught. It will be a class taught by a construction worker (me) to other construction workers. What major events in US labor history do you think would be the most valuable for these guys and gals to learn about? The class is specifically focused on union appreciation. Events that illustrate the importance of workplace unionization are what I'm looking for the most. But any other relevant topics, trends, or events in labor history that you think are important are greatly appreciated.