All your unit needs right here:
World War I:
Introduction (Document that's an Imperialism Picture/Chart)
Causes of WWI
Propaganda Slides in color (6+ of them)
a WWI quiz with word bank and multiple choice/free answer
Crash Course in WWI research assignment. Students work in groups to research various vocabulary/buzz words and present to class. All tied to unit question
Political Cartoon blame assignment. Once I taught WWI used this to facilitate discussion about the blame, viewpoints, and controversy around the end of the "Great War"
You may find this as a great way to open and facilitate your unit. I try to cover as many basics as I can, but I only get a week or so to cover WWI. Students spend much time analyzing and evaluating documents and these are a great way to generate interest.