to the right. Each time you move the block 180?, a cascade of apparently moving blocks will flip to the bottom. There's a neat trick you can play with your Jacob's ladder, which will baffle children (and, most likely, their elders): Fold up a dollar bill into a small rectangle and tuck it under one of the tapes. Then operate the toy. The dollar will successively disappear, appear, disappear, and so on, for no apparent reason. I've seen plans that instruct you to glue the tapes to the bottom and top edges of the blocks. Don't trust them. I have reviewed several ways of making this toy, and I can assure you that gluing does not work. Glue often seeps into the tapes by capillary action, beyond the tops and bottoms of the blocks, and makes the tapes stiff; thus the toy runs poorly or not at all. A better way is to attach the tapes with small headed brads?the larger and thinner the head, the better. The brads hold down the tapes sufficiently well in a simple attachment to the block, and the toy runs very smoothly. 1 Cut out six, seven, or eight rectangles measuring 3 1/2 in. by 1 3/4 in. from 3/8-in.-thick hardwood or plywood. (The number of rectangles depends on the height of the child, or, more specifically, on the distance from the child's hand to the floor.) 2 If you're using plywood, fill any voids in the laminate with fast-drying wood putty, sand well