This bookmark will tell you exactly on which page and at which line to begin reading again.
This bookmark was made from plastic file folders of contrasting colors. Make the size according to that of a typical book. The red piece should be a bit longer than the book is high. The blue piece should be a half of an inch wider than the red piece. If you wish, you may round the corners, especially on the red piece.
Step 1: Cut the Long Piece
I used a sliding paper cutter to cut pieces 5/8 inch wide. For accuracy I measured along the length of the edge to insure the piece has a uniform width.
Step 2: The Slider
The blue piece slides on the red piece. Make the blue piece 1 1/4 inch wide and about 2 1/8 inches long.
I have a hole punch that makes 1/8 inch holes. Make one hole near the top of the slider. Make two holes near the center of the slider.
Step 3: Mark the Slider
Two slots will be cut across the blue slider. Use the red long piece to mark the ends of the slots with dots.
Step 4: Cut the Slots
Use a knife or chisel to cut a slot between each pair of dots.
Step 5: Join the Slider to the Long Piece
Slip one end of the red long piece through the slots in the blue slider.
Step 6: Both Sides Now
You can see that one hole is visible from one side of the bookmark while two holes are visible from the other side of the bookmark.
Step 7: Cut a Notch in the Slider
Make a notch in the slider. This notch will show you the line at which you are to begin reading again.
Step 8: How to Use
When a book is open the page on one side will have an odd number. The page on the other side will have an even number. If you are stopping on a page with an odd number, turn the bookmark over so one hole in the slider will be visible as you open the book from the front cover. One is an odd number. Turn the side with two holes up if you are stopping on an evenly numbered page. Two is an even number. (The page number in the yellow box is 185. The yellow arrow points to one hole in the blue slider.)
Move the slider down to the line where you want to begin again. See the yellow underline. (I have gotten into the habit of aligning the bottom of the page with the end of the long piece of the bookmark, and letting any extra length protrude from the top of the page. If the bookmark moves up or down in the book, I just pull the bottom of the bookmark in line with the bottom of the page and the line indicator is back where I had placed it.)
Open the book from the front cover and you will know immediately on which page and which line you are to begin reading again.