hello, thanks for your question. This is one of those tutorials that I did several prototypes before I got a hood that I was actually happy with so not all the measurements are calculated based on other measurements and can be altered. The original box is 14 1/8 X 17 1/8. This is essentially the width and height of the hood. Yes, the 11 7/8 is based on the neckline measurement. The student can take their neckline measurement from the cloak, divide that measurement in half and use that measurement instead of the 11 7/8. Again, this is just for the base of the hood as it will still be 14 1/8 in the middle of the hood because we want the hood to be loose around our heads and not tight. From the base of the line, I go up 8 1/2″ and draw a dashed line. I don’t know if this is the line you’re referencing in regards to you mentioning 7 1/2″. If so, this is not based on any calculation, just on my personal preference for helping to shape the hood pattern. I hope that helps and that your students enjoy making their cloak! 🙂