Remember that, in a technical writing course, the proposal assignment serves several purposes: (1) it gives you some experience in writing a proposal; (2) it gets you started planning your major assignment; (3) it gives your instructor a chance to work with you on your project, to make sure you have a viable topic. For the second and third reasons, you need to include specific elements in your proposal (as noted in your assignment sheet) some of which may not seem appropriate in a real-world proposal.
The proposal is often the beginning of a weeks-long research and writing process that goes through many stages until it gets to the end point: the technical report. In this case, you only submit the proposal once during this process. After that, you may write and submit different types of documents: a progress report, an outline, an annotated bibliography, a graphics draft, a report draft, and a final report. Be careful to use the term “proposal” only if you are specifically referring to the proposal stage of your project.
Another point to keep in mind relates to the audience for different kinds of documents that may be produced for the same project. Consider the example of a proposal written to a supervisor at a solar power company suggesting the creation of a policy manual for residential solar panel installers. The proposal’s audience may be an executive, whose knowledge of the technicalities may be very broad. Let’s imagine the executive approves the proposal and requests completion of the manual, which will be produced well after the proposal. The manual’s audience is the technicians, who may have more specialized knowledge than the executive. The content and language used for these two different audiences will need to be adjusted to fit the writing situation. (For more on this, review the chapter on Audience Analysis.)