The concept of half-life, and the associated exponential decay curve, can be made more vivid by using piles of pennies (or other stackable objects) to represent atoms.
a. Collect as many pennies as you can find on dresser tops and from coin purses. Fifty to one hundred should suffice.
b. Divide your pile into two equal stacks, placed side by side. The left pile represents the original number of atoms.
c. Divide the right pile in half. Place one of the resulting stacks next to the original left stack. This represents the number of atoms remaining after one half-life has passed.
d. Continue this process, always dividing the remaining right stack in half and placing the stack obtained from division next to those stacks already accumulated. The resulting row of stacks, each one smaller than the preceding one, forms an exponential decay curve. How many half-lives do you obtain before you are down to one penny a stack?