Visual Scientifics pendulum is used to investigate the oscillation period, and has a frictionless mount and an adjustable string for measuring varying changes. The kit includes a pendulum back board, mounting rod, string, and pendulum bob and stopper for hands-on experiments, and has steel construction for durability. Steel is a good general-purpose material, with better weldability and increased rust resistance over wrought iron. The pendulumÃÂ¢Ã¢âÂ¬Ã¢âÂ¢s 20 page instructions cover three hours of class and lab time. The instructions also contain safety information, general theory, classroom lessons, experimental set up diagrams, a student lab book, 10 Next Generation Science Standards Concepts, and 8 Common Core Standards. The kit requires the PTBASE base for operation; optional accessories include a video camera for the extensions, graphing software, and PTPGS photogate (required and optional accessories sold separately).