add readBook function to Teacher constructor add prepareLesson function to Teacher constructor add collect function to Teacher constructor remove backpack constructor remove lesson constructor
add readBook function to Teacher constructor
add prepareLesson function to Teacher constructor
add collect function to Teacher constructor
remove backpack constructor
remove lesson constructor

sheamunion/phase-0-unit-1,sheamunion/phase-0-unit-1,sheamunion/phase-0-unit-1,sheamunion/phase-0,sheamunion/phase-0,sheamunion/phase-0,sheamunion/phase-0,sheamunion/phase-0-unit-1