I used this as an introduction to natural selection. This lab went extremely well, and was actually used for observation (I had school board members, principal, super, etc. in and out of the 2 classes over the 2 days it was done).
Students use fabric environments and paper dots to represent a species of organisms (where different colors represent the trait you are following).
This document includes teacher instructions for set up with tips and pointers for set up and discussion. The lab includes a worksheet with inquiry type questions for the students to begin to understand the mechanisms of natural selection.
Students will also see that some phenotypes might be more beneficial in one habitat than in another, even among the same species.