Fold an A4 sheet of paper in half lengthwise (mountain fold) and then fold up (valley fold) about 3cms for the pocket flap.
Unfold and fold in half, this time bringing the two short edges together (mountain fold). Fold each short side in half again (valley fold).
Unfold the paper and use a craft knife to cut along the centre line between A and B as shown.
Refold along the length of the paper and fold up the pocket flaps. Push the ends so that the cut section opens out and A and B meet.
Fold to make a booklet. Glue (or bind with washi tape) the side edges of the pockets and glue the centre pages back to back.