The second lesson, Radioactive Decay: A Sweet Simulation of Half-life, introduces the idea of half-life.By the end of the 8th grade, students should know that all matter is made up of atoms, which are far too small to see directly through a microscope.Carbon-14 is produced constantly as our atmosphere is bombarded by cosmic rays.It is incorporated into the carbon cycle, so that all living things, including you, contain radioactive carbon-14.However, the carbon-14 that was in the organism at death continues to disintegrate.By measuring how much carbon is left in a sample as well as its radioactivity, we can calculate when the organism died. In this activity, you will work backwards to solve a puzzle, much like scientists work backwards to find the time that an organism died." Procedure Give each student a copy of The Case of the Melting Ice student sheet.The exercise they will go through of working backwards from measurements to age should help them understand how scientists use carbon dating to try to determine the age of fossils and other materials.To be able to do this lesson and understand the idea of half-life, students should understand ratios and the multiplication of fractions, and be somewhat comfortable with probability.
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Having learned earlier that all the atoms of an element are identical and are different from those of all other elements, students now come up against the idea that, on the contrary, atoms of the same element can differ in important ways. 79.) In this lesson, students will be asked to consider the case of when Frosty the Snowman met his demise (began to melt).You can continue to fill the funnels as different classes arrive.Empty the graduated cylinders between classes if the volume is more than about 25 ml.Living things have about 15 disintegrations per minute per gram of carbon.
Because living things constantly interchange carbon atoms, the amount of carbon-14 remains constant, but when organisms die, no new carbon-14 enters the organism.
Students should answer the questions on their student sheet based on their graphs and the data they collected.