Jacob's Ladder (also known as magic tablets, Chinese blocks, and klick-klack toy)
It is "a toy that does some very weird things." When the ladder is held at one end, blocks appear to cascade down the strings. This effect is a visual illusion which is the result of one block after another flipping over. It may be considered a kinetic illusion, where the blocks appear to change position when they do not. Its name Jacob's Ladder comes from the biblical ladder to heaven, mentioned in Genesis 28:12.