Set a clear binder pocket in front of you, oriented sideways with the holes away from you or on top. Measure 7 inches along the bottom, and make a small mark. Hold your ruler at the mark, parallel with the short side of the folder, and draw a light line from top to bottom.
Cut along the line so that the open side, formerly the top, of the folder is snipped off. Discard the waste.
Cut along the bottom seam until just more than 3 inches of sealed seam is left intact. Hold your ruler at the point you stopped cutting, parallel once more to the short edges, and draw a line from top to bottom. Snip off the resulting flap, taking care not to cut the back layer at all.
Insert a number of note cards -- enough to list each item on your "to do" list on a separate card, or whatever number you prefer -- into the pocket that's left. Crease the back flap over the front repeatedly, until the seam is worked enough to remain shut.