You have a clear idea of what you want to say, and a pretty clear idea of how you want to say it, but you realize that you haven't really thought through all of the steps required to get to the end product. You are a bit flummoxed. You could simplify the project. That'll give you the same basic intent, but not the same final result that you'd hoped for. Before you do that, you decide to talk to a few people. You talk to your teacher, you talk to a couple of other teachers in the school who deal with different skills that relate to what you want to do. You even head down to a local makerlab and talke to some of the members there to see what ideas they might have.
You realize that this is adding another dimension to the project that you hadn't initially anticipated. You get some help and ideas and start toward your goal. The whole project takes much more time than you'd expected, but you are learning a bunch of new stuff along the way. You are not only learning some new making skills that you didn't know before, but you are thinking about your topic in different ways and having to do some additional research to fill in some gaps. You get things done on time and are reasonably happy with the result. Of course, if you knew some things when you'd started that you learned along the way, you'd have made some different decisions, but you are generally quite pleased.
You put your project in front of your class and explain it in detail. They really get into it and enjoy exploring the project with you. There are lots of questions about the topic and about the process used in making the end project. You find yourself able to answer all of these questions confidently and in depth. In fact, you surprise yourself a couple of times with the ease with which you answer these questions.
This scenario actually played out in our research. The student had a very clear passion for the topic and idea for how he wanted to share his knowledge, but it wasn't until he started working through the project that he discovered that he didn't have the tools, skills, or materials to pull it off in the way that he wanted to. He almost opted for taking the easy route, even though he knew that it would be much less effective. It was through conversations that he accessed ideas, skills and the means to come closer to what he originally intended.
It is important that we have multiple levels of assessment in these kinds of projects. Failure to realize an end goal can be due to all sorts of reasons, but may have nothing to do with the thought and learning involved in the actual research. This is the constant push and pull between product vs process; between learning and expression of that learning.