This demo is a model of a toy, Jacob’s ladder, that presents as a type of illusion.
What you need:
- cardboard
- scissors
- sticky tape or glue
- pen/pencil
- ruler
- 2x ribbon
What to do:
- Measure and cut out 12 squares of cardboard with 7.5 cm sides.
- Measure and cut 110 cm lengths of ribbon. You will need 1x length of one ribbon and 2x lengths of the other ribbon.
- Place the two ribbons that are the same towards the edge of a piece of cardbaord, starting in the middle and going off the edge. Stick them down.
- Place the other ribbon in the centre of the card, starting in the middle and going off the edge in the opposite direction to the other two ribbons. Stick it down.
- Place a piece of cardboard over the top and glue it down or stick it along the sides.
- Fold the ribbons and run them over the top of the cardboard.
- Put down another square of cardboard.
- Fold the ribbons over and repeat all the steps until you have used all the cardboard. Give a little bit of length between cardboard squares, but not too much, and make sure they are even. Trim any left over ribbon once you’ve finished.
- Hold up your creation by the top square. Bend the top square towards the rest of the squares and watch.
What happens:
If you flip the top square over in one direction, nothing happens. If you do it in the other direction, the second square will flip, followed by the third, then the forth, and so on until the bottom square flips over. It forms a type of illusion where it appears that all squares change position. In actual fact, each square is just moving down, depending on the location of the first square. This happens because the ribbon is stuck on one side of the square, but on the other side it is loose, which allows it to rotate around the bottom edge.