What’s an unfinished block?

An unfinished block has not been sewn into a quilt. It has not been sewn to another block or to the sashing in the quilt.
An unfinished block has a 1/4 inch seam allowance on each edge…making the unfinished block 1/2 inch larger than the block when it’s “finished.” (1/4 inch on one side plus 1/4 inch on the opposite side of the block equals 1/2 inch.) When the block is finished the 1/4 inch seam allowance on each side will be sewn and pressed under. So, a 12 1/2 inch unfinished quilt block will create a 12 inch finished block.