MEANING OF A DOT - Through a series of graphic demonstrations Mr.Wizard and Shan define what a dot means, whether in musical notation, typographic setting or in mathematics a dot is based on it's surroundings. SINGING ROD - Mr.Wizard strokes a metal rod to produce a musical tone. He and Wensley develop that the friction of rubbing vibrates the rod which produces the tone. Wensley thinks the sound is similar to feedback, but Mr. Wizard thinks it is more pleasant. They review how to get a rod to produce a tone. Wesley strokes it to produce the sound. MARS BALL – Mr.Wizard narrates : This weird vehicle is for carrying TV cameras and scientific instruments for exploring the surface of Mars. It’s one of the designs underwritten by the National Aeronautics and Space Administration. SHAKING COLOR - Kellie observes three bottles that appear to be half filled with water. Mr.Wizard suggests she shake one of them three times. When she does, the solution turns blue. She shakes the other two bottles and the solution in them also turns blue. By now, however, the first bottle is losing its blue color. When she shakes it, the blue color returns.The color change takes place when methylene blue reacts with the oxygen in the air above the solution when she shakes the mixture. As the oxygen is used up, the blue color fades. LIGHT ACTIVATED WEED KILLER – Mr.Wizard narrates: One way to kill weeds is to spray them. Unfortunately, chemicals that are strong enough to kill weeds can effect other plants and animals. At the University of Illinois at Banner-Champagne, scientists are testing a weed killer that’s triggered by light. In tests, a concentrated dose of amino acids is sprayed on the plant which is then covered with foil so that it gets no light. In the dark, the plant absorbs the chemical. Since the amino acid loses its strength in 24 hours, it should be environmentally safe. In the future, when the herbicide can be produced economically in large quantities, farmers could spray the weeds at night. This time-lapse sequence shows what would happen when the sun comes up. The plant on the left has been sprayed. When it is exposed to light, it withers and dies because of the weed killer triggered by light. BRIGHT SPOT TESTER - Mr.Wizard has an apparatus set up with a 25-watt bulb at one end and a 75-watt bulb at the other. Brian knows the 75-watt bulb will be brighter and assumes it will be three times as bright because three times 25 is 75. They set out to find the answer. TAKING WATER APART - Christina knows the formula for water is H2O. Mr. Wizard shows her the apparatus that uses electricity to take water apart. She identifies which test tubes contain hydrogen and which oxygen by the fact that there is twice as much gas in the hydrogen test tubes. They perform the test. RED WOLF – Mr.Wizard narrates: This is the wilderness along the coast of North Carolina where an important natural predator was the red wolf. In this vast area, where once there were thousands of red wolves, there are only three pairs and they were flown in by helicopter. Wolves are raised in a special compound run by the U.S. Fish and Wildlife Service in the State of Washington. FOAMING COLOR CHANGES - Sarah has used litmus paper in school to test solutions. Mr.Wizard introduces her to a universal indicator that is blue in the presence of a base and yellow in the presence of an acid. She pours a base liquid which is blue into a glass and adds a piece of dry ice. The solution changes from blue to green and finally to yellow as the solution absorbs some of the carbon dioxide gas given off by the dry ice. Sarah continues to add blue liquid that changes to green and then yellow until the glass is almost full of solution.