Converting a 12" block to a 6" ... divide in half and add 1/2", right. Easy peasy. WRONG. I still don't know what happened; too mad to mess with it right now.

Take a deep breath you will get it. Try, try and try again. BrendaK

:oops: I would've done the same! Thanks for the warning.

If you place a 6" square piece of paper on a 12" one, you will see you needed to divide it by 4, then add your 1/2" seem allowance

Sorry to object, but you have to divide the length measurements by two otherwise you end up with a 3" block. CompulsiveQuilter seems to have done it correctly but somewhere a mistake must have snuck in. What kind of block was it and what size block did you end up with? Maybe we can work out the mistake when we know the details.

I can "see" divide it by 4 but it doesn't make sense in my head. Why does that work? Six is half of 12. This makes my brain hurt.lol

It is hard to give advice unless we see the block.
Depends on if it is a square or a star.

Did you divide the original measurements for the 12" block, the ones that included the necessary seam allowances for the 12" block?

Are you trying to reduce/enlarge individual pieces or the whole block at one time?

The op is talking about the individual pieces that make up the block.

So if you have a four 6" finished blocks making up a 12" block, you do want to divide each piece by 2 and add the seam allowance.
That will give you four 3.5" blocks, which will make a finished 6" 4-patch block.

Your way would have four 1.5" blocks, with a finished block size of 3", which would be too small for what she wanted.