Using the 2010 Synthesis Question (about schools and technology), I've created a brainstorm and outline assignment for students in order to practice how to think through a well-reasoned and structured argument or synthesis essay.
I have the prompt here, however, I use it in two ways: First, I have students treat the prompt as an argument prompt. They brainstorm and plan their essay using their own thinking and evidence. Next, I show them the synthesis packet and we repeat the activity, this time using the sources to support our position. I like students to see the similarities and differences between an argument and synthesis essay, and how they can approach the essays in a similar manner but need to treat the writing process differently (this means I copy the handout twice for each student).
Of course, you can use this assignment for either essay prompt on its own. I ask students to brainstorm, write thesis statements, and plan supporting paragraphs. I have it here as a PDF, but if you would like it in a Word document, feel free to message me :)