The spring only needs to be compressed and does not oscillate. It should begin in the compressed position (for simplest scenario). When the spring is released, the object is launched and moves along a horizontal surface where it is slowed by the friction of the surface.
Changing the spring constant or mass amount should be accompanied by a visual change (size?) in the spring and mass. Changing the friction of the surface should also be shown by a visual change in the attributes of the surface and the distance the object moves.
A pinball machine or gun loader mechanism comes to mind. Most of the scenarios involve the stored elastic energy of the spring being compared to the resulting kinetic and thermal energy of the object.