Attach an upward facing needle to the sinker. Drop a styrofoam cup with water falling out of a hole and watch what happens. When an object falls the effects of gravity are cancelled out and an object experiences weightlessness. In this case, the frame and the objects inside become weightless. However, if the lead sinker becomes weightless, the elastic bands, which are stretched, will now pull the sinker up causing the needle to puncture the balloon.
Many strange things happen with falling objects due to the effects of gravity being cancelled out.
For example, fill a styrofoam cup with water and put a hole in the bottom side of the cup with a pencil. See if you can come up with your own falling demonstrations that might produce other interesting effects. This site is optimised for Netscape 2.01 or Internet Explorer 2.0. or higher.