Question about Dessert Time pattern by Eleanor Burns
 

Okay, I am a new quilter, so I am trying to understand the why and reasoning behind a pattern I just purchased. This pattern claims it is for the beginner, and you can use 10 inch precuts. But then you must trim down 40 10 inch squares to 9 inch squares. Yikes!
Now what would be the reasoning for this? If I left my 10 inch squares as is, would it make this quilt look strange? I am really trying to understand this, and i understand that I will need more fabric for the borders, etc, but that sure seems to make more sense to me than cutting down all of these squares.
I am going to make it as instructed, (After I purchase a 9 1/2 inch square ruler! ) but I am trying to understand the logic behind it. Why wouldn't the person who made this have left the precuts as is so it would have truly been an easy quilt for a beginner? Do triangles from 10 inch squares look bad compared to triangles from 9 inch squares?

Look here: https://www.youtube.com/watch?v=Q7eR_h7ZrDE

I would make the block using the 10 inch squares and then trim down after making. All precut pieces may not be exactly 10".

You need to start with 10 inch to get the 9 inch block. The extra is taken up with the seam. Seeing on the angle takes up more than sewing a straight seam

OK, remember your high school math?? When you start to get into HSTs, you have to realize that you need to add 7/8" for a seam allowance instead of the standard 1/4" we become so accustom to. If you need to make a 9" HST, you need to cut two squares 9.875" So most quilters just add an inch and then sliver trim down the block. it may take a little more time, but you will have an accurate block.

Good advice here.
I just want to welcome you to this board. Lots of helpful and knowledgeable people here.

Thanks for all the responses And this video will be very helpful!!! Feeling better about it already!

Eleanor always gives you a fudge factor, just in case you need it.

wonderful pattern... and welcome to the QB! You'll love how knowledgeable these members are and so willing to offer assistance. We look forward to seeing pictures of your quilt.

Welcome to the QB. I have learned so much here.