What happens when university curriculum developers are mixed with motivated elementary teachers? ? An awesome learning collaboration that benefits researchers, teachers, and students! That's what the authors discovered when they--university researchers involved in the Physics for Elementary Teachers (PET) project--teamed up with local elementary teachers to develop effective inquiry-based physics lessons for second and third-grade students enrolled in an after school science program. Everyone gained from the teamwork--this article describes their experiences implementing a collaboratively developed lesson on friction.