1. A compression pad apparatus for CPR training, the apparatus comprising: a housing comprising a first cover and a second cover opposing the first cover, the first cover comprising a first interior surface and a first exterior surface facing away from the first interior surface, the second cover comprising a second interior surface and a second exterior surface facing away from the first exterior surface and further facing away from the second interior surface, the first and second exterior surfaces being generally planar and generally parallel to each other; a printed circuit board (PCB) comprising circuitry and interposed between the first and second covers; at least one force sensor connected to the circuitry and configured to detect force applied to the compression pad apparatus; a plurality of contact sensors comprising a plurality of contact patches and at least one set of contact patterns; the plurality of contact patches provided on the first interior surface such that the plurality of contact patches are arranged generally surrounding the at least one force sensor when viewed in a direction perpendicular to the first exterior surface, wherein the plurality of contact patches are made of an electrically conductive material and are not electrically connected to each other; and the at least one set of contact patterns formed on the PCB, wherein each set of contact patterns comprises two or more electrically separate conductive patterns that are connected to the circuitry of the PCB and exposed toward at least part of the plurality of contact patches; wherein each contact patch faces a corresponding set of contact patterns formed on the PCB such that the contact patch does not contact its corresponding set of contact patterns when no external force or compression is applied to the housing in the direction perpendicular to the first exterior surface and further such that the contact patch contacts its corresponding set of contact patterns when external force or compression is applied in the direction to the housing in a portion corresponding to the contact patch, wherein the circuitry of the PCB is configured to generate contact signals when at least one of the contact patches contacts its corresponding set of contact patterns in response to external force or compression applied onto the housing.