This is not the best wording, but it's what I have for now: Label the top, left, bottom, and right edges of the square T, L, B, and R, respectively (so T and L

This is not the best wording, but it's what I have for now: Label the top, left, bottom, and right edges of the square T, L, B, and R, respectively (so T and L are the ones which must be glued to each other, in suitable fashion). Cut the square down the \ diagonal; this produces two pieces: an L\B triangle and a T\R triangle. Mark the \ sides of these pieces as having to be ultimately glued to each other in the appropriate fashion, and now re-attach them in the way in which L and T are already indicated to be glued (in the process, flipping one of them over). Now one has the equivalent of the M diagram from before, and thus a Mobius strip.