The homework assignment, given last week to a class of about a dozen students at the Vägga School in Karlskrona was meant to teach the student about Swedish nouns which change form from singular to plural.
The Swedish word for 'rule', regel, becomes regler when written it is plural form.
Among the words that appeared on the worksheet was neger, a Swedish term for a black person which translates roughly as Negro and is considered by many to be derogatory.
"It's absolutely not appropriate," principal Eva Kindell told the local Blekinge Läns Tidning (BLT) newspaper.
Kindell claimed she only learned of the lesson after it had been handed out after a copy of the worksheet was sent to her by a teaching assistant assigned to help immigrant students.
"It's a very unfortunate example and a work that people really don't use any more," she told the newspaper.
"It's stigmatizing and absolutely inappropriate."
The teacher suspected of handing out the assignment doesn't want to admit to any responsibility for the offensive worksheet.
Kindell said she plans to investigate the matter further, but couldn't say how long the material had been used or whether it has since been removed.
She guessed the neger worksheet was from an out of date grammar book, explaining that the school had access to updated material and that "a lack of awareness, thoughtlessness, or an oversight" is likely to blame for the assignment being handed out to the immigrant students.
Kindell couldn't say, however, whether the teacher in question would be formally disciplined.
"I can see that we need to have a serious conversation about this," she said.