This activity uses the PhET Resonance simulation, found at: http://phet.colorado.edu/sims/resonance/resonance_en.html. Students will study free springs or pendulums prior to this activity, where the meaning of ‘free’ is a hanging spring or pendulum that is simply started in oscillation, with no other external forces trying to change its oscillation (outside of air friction, which decreases the amplitude of the oscillation). Students will be able to vary a number of parameters within the simulation. These parameters are frequency and amplitude of the mechanical driver (like the person pushing a swing), the spring constant, mass attached to the spring, and the level of damping in the system. Students will also be able to have multiple springs in the simulation which will allow them to compare and contrast the effects of changing parameters. This computer simulation experiment will allow students to investigate what resonance means for oscillating springs. The experiment can be a true inquiry experience for students, since details about resonance are generally not well-known. Student Outcomes • Explain the conditions required for resonance. • Identify/explain the variables that affect the natural frequency of a mass-spring system. • Explain the distinction between the driving frequency and natural frequency of a resonator. • Explain the distinction between transient and steady-state behavior in a driven system. • Identify which variables affect the duration of the transient behavior. • Recognize the phase relationship between the driving frequency and the natural frequency, especially how the phase is different above and below resonance. • Give examples the application of real-world systems to which the understanding of resonance should be applied and explain why.