Prepare a final report or presentation based on their findings.
I think it would be exciting to use part of the "Square of Life" in my PBL. We could either sign up to share with other schools via the Square of Life website, design a district-wide site for the Cedarburg kindergartens to compare the 3 elementary schools, or network and find other schools within the state, country and/or world to share with.
In addition, if anyone else K-12 is looking for ideas I would highly suggest checking out CIESE!