 How does Teena find out about radioactivity?
Still, one clue is as good as another when it comes to hunting uranium ore, I guess. It could start cavities. Get at it right away, and you’ll still have time to hunt your uranium. In fact, anything having to do with atomic science excited him. You couldn’t have a father who was head of the atomic-science department at Oceanview College without picking up a little knowledge along the way. Eddie knew that a radioisotope was a material which had been “cooked” in an atomic reactor until it was “hot” with radioactivity. When carefully controlled, the radiation stored up in such isotopes was used in many beneficial ways. One reason for asking that particular question was to keep from prying deeper into the subject of the radioisotope. At the speed atomic science is moving today, we simply can’t afford to waste time. “Anything else, Mom?” he asked, returning to the house and getting the Geiger counter out of the closet. Besides, there were plenty of other places around the outskirts of Oceanview where likely looking rock formations invited search with a Geiger counter. 19 Christina Ross—whom everybody called Teena—lived at the far end of the block. 20 Eddie went inside and followed Teena to the kitchen. They had been ever since Eddie’s family had moved to Oceanview and his father had become head of the college’s atomic-science department. Teena’s father was chief engineer for the Acme Aviation Company, one of the coast town’s largest manufacturing concerns. 22 “Oh, yes, it’s fun, Mother,” Teena replied, wrapping wax paper around a sandwich. At various rock mounds and outcroppings, Eddie switched on the Geiger counter. There were slight traces of radioactivity in almost all earth or rocks. It was in the air itself, caused by mysterious and ever-present cosmic rays, so there was always a mild background count when the Geiger counter was turned on; but to mean anything, the needle had to jump far ahead on the gauge, and the clicking through the earphones had to speed up until it sounded almost like bacon frying in a hot skillet. After they had hiked and searched most of the forenoon, Eddie said, “We might as well call it a day, Teena. Then he told Teena about his dream. It was midafternoon by the time they arrived back at Teena’s house. They worked a while on a new jigsaw puzzle Teena had received on a recent birthday.
 Eddie teaches Teena and her mother about about radioactivity after the news gets out about Mr. Taylor’s isotope being stolen.
 Eddie teaches her about radioactivity during their hike to Cedar Point.  Eddie teaches her about radioactivity while he helps her finish doing the dishes.  Eddie teaches her about radioactivity when he is explaining the dream he had about Cedar Point.  Eddie teaches Teena and her mother about about radioactivity after the news gets out about Mr. Taylor’s isotope being stolen.