The Motion of a Pendulum lab uses a mass on a string to investigate the relationships between the mass, length, amplitude, and period of oscillation of a pendulum. It is part of High School Virtual Physics Lab, a set of 24 iPad apps for use in the classroom. To see how they work, try the FREE HSVPL Newtons 2nd Law lab.In addition to a 3D simulation that produces realistic data, each lab includes introductory videos, background theory, experimental procedure, analysis and reporting tools, pre- and post-lab quizzes, and teacher support materials.These labs can serve as replacements for hands-on labs, especially when equipment is not available, or as supplements to hands-on labs. They are also a suitable option for students in distance learning situations. Formative and summative evaluations showed no significant difference in learning between students using the virtual labs and those using hands-on labs. Preliminary results suggest increased learning by students using the virtual labs as supplements to hands-on.HSVPL was developed by Polyhedron Learning Media, Inc. and is distributed in conjunction with Houghton Mifflin Harcourt. Funding for this project was provided under contract number ED-IES-11-C-0029 by the Institute of Education Sciences in the U.S. Department of Education through the Small Business Innovation Research (SBIR) program.