I always work with a narrower width of fabric (not the whole width). I tear about 18 inches down the length. Flat head pins are a must. And only work on one block at a time. This is not a pattern to do chain sewing with.

I am so glad that what I read wasn't right about not prewashing the material. I really don't like to use unwashed material when I sew. All that time and effort down the drain if it shrinks funny and all :(

A OBW is on my to do list for early next year.

Which one are you going to do. I did the original pinwheel which at that time came in a pattern so didn't have to buy the book.
Best hint I can give is get some paper plates and put each block in the plate. It helps keep all sorted out and harder to mix up.

I just finished a top that is a stack-n-whack and I washed all my fabric first. Mine is more like stained glass. No 2 are alike. Stack 6 squares and cut 3 times differant ways.

I used the paper plates for my OBW, it did make it easier to keep them sorted.

If you slightly distort your fabric when washing or pressing, your fabric will not line up correctly for stack and whack or OBW just saying :D:D:D

Linda, are you saying "straight pins are a must"????? or are you saying specifically "flat head" ??????? pins are a must. I am also taking a class on Stack N Whack. The teacher uses flat head pins.
I don't have any. Do I need to buy some???? If yes, how are they different from a rounded head straight pin?

Flat head pins are almost a necessity..

I always wash fabric, (in the washer and dryer and fold as it comes out of the dryer), before putting it in my stash at home and when doing a pattern like the stack/whack, starch and iron it before cutting. "I " haven't had any problems with it being off grain or messing up the ability to line up.. maybe it's the fabric but I would not want to cut and sew any fabric without washing and drying.

I recently read an article about newly purchased fabric. Because there is an 'epidemic' infestation of bed bugs going around, it is recommended that ALL fabric be put into the dryer on hot, as soon as it is brought home, for about 20 minutes to kill all larvae or eggs that may have attached itself to the fabric when it was being shipped here in containers. Not a nice topic but better safe that sorry. It would just kill me to know my very large stash had tenants.

Thank you Rntraveler, I will get some. Can you tell me more about the benefit of using the Flat Head pins specifically?

The flathead pins are for when you put your ruler on your fabric to cut, it lays flatter, so you don't tend to move the ruler. If you tried to put your ruler over round head pins, it would wobble, and you won't get a straight cut.