Originally Posted by L'il Chickadee

True, true. Had the group leader asked for a volunteer rather than singling out someone to take on the task, things could progress with no hard feelings. Good diplomacy would have allowed a volunteer the ability to say there is no way to accomplish this goal without a change in the block size. As it is, either the person tasked with presenting instructions is seen as a failure or the group leader is put on the defense as soon as she's told this block size can't be done.
However, it can be pulled off.
You whisk into the meeting with instruction sheets in hand and a bright smile. Announce that you have the block instructions, but we must first be open to a small change in the block size. This accomplishes two things, first the assignment is done, second without pointing fingers the group is given a choice on how to move forward.