This worksheet on Biological populations with non-overlapping generations has three parts. In the first two parts we look at the model itself, and especially at the long term behaviour of the trajectories and how this may depend on initial conditions, growth parameters, etc. In section 1 we consider the dynamics of a single species; in section 2 we consider two competing species. The third part (originally bifurc.ms) introduces the idea of a bifurcation diagram, which is a record of the repeated "stable points" that occur for different growth parameter values.