A toy may include a housing, an electromagnetic-field sensor, an output, a controller, and/or a source of an electromagnetic field. The housing may be adapted to be supported on a support surface. In some examples, the housing may support the field sensor in a fixed orientation or position relative to the support surface. In some examples, the field sensor may be adapted to produce a signal having a magnitude representative of a change in a field passing through the sensor. In some examples the output may have a changeable sensible output. The controller may be adapted to operate the output to have different outputs for different magnitudes of the signal. The source of the field may be moveable by a user relative to the sensor to expose the sensor to a field that changes according to the movements of the source by the user.