A high school chemistry teacher was arrested after students claimed he taught his class how to make a bomb, authorities said. David Pieski, 42, used an overhead projector in class to give instructions in making explosives to students at Freedom High School, including advising them to use an electric detonator to stay clear from the blast, an Orange County sheriff's arrest report said. In Pieski's classroom in Orlando, authorities found a book labeled "Demo," which includes the chemical breakdown for a powerful explosive, the arrest report said. One student said he set off an explosive device at a golf course...