Hello Jessica,
Thank you for your question.
Figuring out headings can be a real hassle. You are correct that a cell 7 heading is applied to the lowest hierarchy levels in print. However, there may be different text elements that can be considered the “lowest level” depending on the book’s layout.
As for your example, it appears to me that the hierarchy would be:
Modeled and Guided Instruction, Read, Genre: Science Article, Beaver Lodges by Bryan Davis.
In this situation, I recommend making them all centered headings. The way you have it now, the headings Read and Genre are subheadings to the story. In reality, the story title is a subheading to the Genre. Since the story heading should be centered, making the rest of the heading centered will allow you to place them one after another with a blank line between them. The centered headings could then be used throughout the book for other similar headings.
Mike