【明報專訊】Have you heard of optical illusions? The word ''thaumatrope'' (留影盤) means ''wonder turner''. It is a toy that was popular in the 19th century. You can see two images blending into one when you spin it fast!

◆Materials and tools

•A piece of paper

•Colour pencils / crayons / markers

•Two rubber bands

•Scissors

(1) Cut a circle or a horizontal oval from a piece of paper.

(2) Think of two images which go together. Draw one item on each side of the paper. One image should be upside down.

(3) Make two holes on the far right and the far left.

(4) Insert a rubber band in each of the two holes and put it through itself to make a knot.

(5) Hold a rubber band in each hand. Flip the paper repeatedly until the rubber bands are twisted tight. Pull the rubber bands apart to create the effect.

◆Quick tips

˙Use thicker paper such as construction paper for better effects.

˙Make use of something round to help draw a perfect circle.

˙You may use a straw instead of rubber bands.

˙Pay special attention to the positions of the two items when you draw so that they can be blended into a perfect picture later.

˙Partnering images can be a boy and a football, a magician and a magic wand, a bird and a cage, a surfer and waves, etc. You can think of your own creative pair. (See picture 6)

■Glossary

optical illusion (n) 視錯覺

blend (v) 交融

upside down (adv) 上下顛倒

surfer (n) 衝浪者

[Smarties' Power English 第259期]