Births and deaths are always happening in a population. How does the number of births and deaths in a population affect its size? To find out, try these missions:

Mission 1: Make the population size stay the same over time.
Mission 2: Make the population size increase over time.
Mission 3: Make the population size decrease over time.

Add 14 tokens to the circle on the Token Model Population Circle sheet to start with a population of 14 organisms.
Every year 1, 2, or 3 organisms must die and 1, 2, or 3 organisms must be born. How many is up to you and your partner.

To make an organism die, remove it from the population and add it back to the cup. Count this as one death.
To make an organism be born, add one token from the cup to the circle. Count this as one birth.
Repeat until you have modeled 6 years.
At the end of every year, record the number of births, deaths, and organisms on the chart and plot the number of organisms on the graph.
At the end of 6 years, add up the total numbers of births and deaths and record it in the total column.
When the population size stays the same over time, the total number of births the total number of deaths.
When the population size increases over time, the total number of births the total number of deaths.
When the population size decreases over time, the total number of births the total number of deaths.