The apprentice shall enroll and attend classes in related subjects at a school or other shop training facility approved by the State Apprenticeship Office for not less than 160 hours or as approved by USDOL/OA per year. The apprentices shall also take advantage of provided instruction in recognized apprentice classes during periods of temporary unemployment. School attendance in all cases shall be obligatory; failure to attend these classes in related instruction may cause the apprentice to be disciplined or his apprenticeship agreement annulled. Apprentices are to attend school on their own time, and such school attendance shall not be considered as hours worked. The local apprenticeship committee shall not recognize any apprentice with whom they have not signed an apprenticeship agreement or who is not registered with the Department of Health and USDOL/OA.