Put the blackboard without anything written on it and a chalk inside an envelope and leave it on a table. Now, ask ghosts to show they are present by writing on the blackboard. Then, you will take it out of the envelope and read the messages from the other world!
The magician turns the chalkboard and the prediction matches with the freely thoughts of the audience. ... The Lynx Blackboard has a diabolic electronic system developed in the last 3 years, which allows the magicians' predictions appears written in real chalk and enables to do true miracles in mind reading or predictions.