You always need to end up with the conventional task. You do not need to start with a case; choose for the first task the one that students could handle based on their initial level. You also do need to design the whole intermediate types of tasks but be sure that students can smoothly go from the first one to the conventional one.
Remember that each task should be the simulation of your whole real-life problem that demands students to use the system of skills. That is why I suggest you go back to your real-life problem and compare each task with it; they should match!
Book design is the art of incorporating the content, style, format, design, and sequence of the various components of a book into a coherent whole. In the words of Jan Tschichold, "methods and rules upon which it is impossible to improve, have been developed over centuries. To produce perfect books, these rules have to be brought back to life and applied."
Front matter, or preliminaries, is the first section of a book and is usually the smallest section in terms of the number of pages. Each page is counted, but no folio or page number is expressed or printed, on either display pages or blank pages.