Select 250g mass and attach it to Spring 1. Press red stop button at the side of Spring 1 to stop oscillations. Measure and record value for extension of Spring 1 with 250g mass attached. Pull mass downward away from its equilibrium position for an extension between 10 cm and 20 cm and release to begin oscillations. Use stopwatch to time for ten (10) oscillations. Do two time trials and get average of these two runs.