In theory, if you can get rid of the friction, it would keep going but with no friction, a yo-yo wouldn't work. By means of mechanical action, the device is supposed to be restored to it's starting point. Hold an invention convention where students are invited to design their own perpetual motion device. Have the other students evaluate them to discover where the flaws lie and explain how they violate the law of conservation of energy. There are many folk tales suggesting where warts come from, the truth of the matter is that you can't get them from toads, frogs on any other bumpy, lumpy animals.
Warts are small skin growths caused by one of several types of viruses.
While they are not life threatening and are usually painless, the viruses that cause them are potentially contagious. Most warts appear as a round, raised lesion on the skin having a rough, dry surface. Planter's warts which occur on the sole of the foot can be quite painful because they rest on a pressure point. Have the students poll their relatives and friends on their favorite wart removal methods and discuss them in class. When it comes to predators, none are more ferocious than sharks.