One characteristic of radioactive material is that radioactive isotopes
spontaneously give off particles. This process, called radioactive decay, changes the nucleus of the material. The length of time it takes for half of a sample of radioactive material to decay is called the half-life. Each radioactive isotope has a characteristic half-life, ranging from less than a second to millions of years. In this activity, you will use pennies that can land heads, to represent nuclei that have undergone radioactive decay, or tails, to represent those who haven’t. as a simplified model of how half-life is determined.