Hello Duane,
This is a great question! The functionality found in the Agile Teams experience that helps our customers create iterations to plan and manage work over a period of time is not directly supported in our Projects experience. I think this is interesting feedback and I would love to hear details about how you would prefer to work with the projects as this functionality is something that we are considering for the future.
I imagine, however, that you could potentially simulate that work process by creating projects that are based on the overall value you want to accomplish during a specific time frame (iteration) that only hold the work that you commit to completing for that time frame. In your example, if you are at the end of an iteration time frame and you have a list of tasks that have not been completed, you could talk about moving those or breaking them down to an upcoming project. And of course, you could also use the agile view in the project task list to visualize the work items in their statuses.
If anyone else reading this has some other suggestions on how this could be accomplished today, please share them here.