Even though the schoolday hasn’t gotten any longer in the last half-century, the teacher’s work-week has. Their current 50-plus-hour week is the longest on record.

How many hours do you work per week - over time (revised)

Also of note: in 1961, elementary teachers worked longer hours than secondary teachers, but that situation reversed in the early 1970s, and secondary teachers have worked longer hours ever since.

Source: National Center of Education Statistics

Disclaimers: We can’t trust surveys blindly. I mean, we can’t trust anything blindly, but in particular, we don’t know exactly how this question was phrased, or what inaccuracies may creep into teachers’ estimates of their own workload.