(1) All persons registered as apprentices or trainees with the state apprenticeship council and participating in supplemental and related instruction classes conducted by a school district, a community college, a vocational school, or a local joint apprenticeship committee, shall be considered as workers of the state apprenticeship council and subject to the provisions of Title
51 RCW, for the time spent in actual attendance at such supplemental and related instruction classes.
(2) The assumed wage rate for all apprentices or trainees during the hours they are participating in supplemental and related instruction classes, shall be three dollars per hour. This amount shall be used for purposes of computations of premiums. For purposes of computing disability compensation payments, the actual wage rate during employment shall be used.
(3) Only those apprentices or trainees who are registered with the state apprenticeship council prior to their injury or death and who incur such injury or death while participating in supplemental and related instruction classes shall be entitled to benefits under the provisions of Title
51 RCW.
(4) The filing of claims for benefits under the authority of this section shall be the exclusive remedy of apprentices or trainees and their beneficiaries for injuries or death compensable under the provisions of Title
51 RCW against the state, its political subdivisions, the school district, community college, or vocational school and their members, officers or employees or any employer regardless of negligence.
(5) This section shall not apply to any apprentice or trainee who has earned wages for the time spent in participating in supplemental and related instruction classes.