The student got a warning as the assignment was done without help.
Those taking humanities courses accounted for 13 of the misconduct or cheating cases. The sciences had eight, and health sciences and commerce had six each.
Two cases involved PhD students.
The university's annual disciplinary reports also show its proctor dealt with 576 offenders overall last year, up from 482 the previous year.
But proctor Dave Miller said students' attitudes towards unacceptable behaviour were moving in the right direction and pointed to the incidents of fire-lighting which had steadily fallen since peaking at about 250 in 2011 and 2012 to 128 last year.
"Last year, we noticed an increasing trend in students not tolerating unacceptable behaviour in their community. Many were increasingly vigilant and drew attention to poor behaviour," Mr Miller said.
"We view this as a positive trend as we work with the student community towards improving the safety and enjoyment for everyone in North Dunedin," he said.
There was "more to be achieved", but the message seemed to be "getting through that the university has no tolerance of fire-lighting and bottle throwing".
The number of students involved in serious enough incidents to be referred to the provost dropped from 27 in 2014 to 22 last year.
The number of students in the most serious category, who are referred to the vice-chancellor, Professor Harlene Hayne, rose from nine to 12, with six of those expelled for a semester.
Among those expelled were a student who stole a couch with a group of students and then set it on fire and another who broke a flat window, injuring three of the flat's occupants.