It is ironic that, in Last Lesson of the Afternoon by D H Lawrence, it is the teacher who is waiting for the school bell to ring to "end this weariness" and not the students. The children he is trying to teach are "My pack of unruly hounds" which shows how difficult it has become to impart any useful knowledge and he can "urge them no more." They show little respect for their subject and their books contain "several insults of blotted pages." He feels that it is a futile exercise due to the "scrawl / Of slovenly work that they have offered me."
The teacher questions whether he can be expected to "waste myself to embers for them" and use up "The last dear fuel" which suggests he will just burn out and there is no reason "to consume Their dross of indifference" which will reduce him to nothing more than "a heap of ashes of weariness."
The repetition regarding his "weariness" stresses his feelings. To ensure that he does not "hate them - I will sit and wait for the bell." It is clear to the reader that he is resigned to just waiting, thereby keeping "Some of my strength for myself."