The electroscope: a measuring instrument built by yourself

For this experiment you need:

• scissors,
  
• one roll of aluminium foil,
  
• a toothpick,
  
• a high drinking glass or a vase,
  
• a longish piece of plastic,
  (for example this could be a comb, a ruler, a bicycle pump, a plastic bottle, a convoluted plastic folder or also a blown up air balloon.)
• and a piece of wool or fur.
• (A pullover made of wool, a piece of leather or lamb's wool would be ideal.)