Give It a Whirl quilt
 

I was in keepsake quilting and looked at kits. one was Give It A Whirl and came with a video. she started with ten inch pieces, placed two together and sewed all around the edges. then cut X across to make hst's. then she trimmed each hst to 6 1/2 inches. how did she get four 6 1/2 inch from ten inch cuts of fabric? must have been larger. i just can't see it if not. she then adds strips so each one is 8 1/2 and four together makes 16 inch blocks. anyone made this? OK< my lovely son said it's because the cuts are across the corners. makes each cut and sewn hst larger. my poor brain is going to bed. i know he's right but still, such a simple thing and it eluded me! nighty night

There are many patterns that cut diagonally across and the block will be bigger then the starting size. Amazing how many will say that is not possible. LOL

Someone will be able to respond with the proper math explanation but remember they are sewing 2 10" pieces together and cutting on the diagonal.
i have not made this quilt.

I've never made that pattern, but I just drew a rough sketch on graph paper (I'm not that good at my geometry anymore :o ) and I have no idea how she gets 6 1/2 inch.

It's because with TWO 10" pieces of fabric, the area is 200 square inches total fabric. The diagonal measurement of 10" square is 14" inches. That would leave you with four 7" squares after cutting both directions, then the seam allowances take up 1/2". That leaves you with four 6 1/2" HST's.

Yes, it's simple. The diagonal of a 10" square is about 14" so the outside edges of the HSTs would be more than 6".

BUT the reason I do not recommend this method for HSTs is because the resulting HSTs have bias edges along their outside edges, yuck!

Try cutting your basic squares at 10" -- or maybe even 10.5" -- draw a diagonal line in each direction and in half thru the middle both directions.

Sew 1/4" away from those two diagonal lines, on each side of them. Then cut on the drawn lines. Press and trim.

Jan in VA

CORRECTION!! Mistake in the drawn lines/cutting lines in the above comment:
Please disregard the vertical and horizontal lines -- do not draw or cut on these. The graphic was created for another purpose but can serve for this explanation if the lines thru the middle of the square are ignored.

Thanks! Sorry!

Jan in VA

OK, here's the math. The diagonal measurement of a square is roughly 1.41 times the length. So the diagonal measurement of a 10" square is a bit over 14 inches. When you cut the X in the square you cut the diagonal in half, so each HST is 7" less the seam allowance.
But I'm with Jan. Even if I starch everything, I pull these bias pieces out of shape. Most people have no problems with them, however.

agree with Cass62 - think of the "volume" of the fabric squares, not the outer dimensions... two 10" pieces = 200 square inches - divide by 4 (the final number of squares) to get 50 square inches per final square...the seam allowances reduce the measurable square inches per final square. 50 square inches is roughly 7 x 7 inches....

Jan, I may be missing something here or just plain dense (probably the second!) but don't you still end up with bias edges on the outer edges of the produced blocks?