The term "apprentice," as used herein, shall mean a person at least sixteen years of age who is covered by a written agreement, acting as employer's agent, and approved by the Apprenticeship Council, which apprentice agreement provides for not less than four thousand hours of reasonably continuous employment for such person for his participation in an approved schedule of work experience and for at least one hundred forty-four hours per year of related supplemental instruction. The required hours for apprenticeship agreements may vary in accordance with standards adopted by local apprenticeship committees, subject to approval of the State Apprenticeship Council.