"We do encourage students to sit external examinations but the nature of the NCEA qualification being what it is, means that some students do not need to sit the exams."
Prangnell said if classes had small numbers the school ran multi-level classes or correspondence courses.
The Ministry of Education's associate deputy secretary of early learning and student achievement, Pauline Cleaver, said there were several reasons why student numbers changed.
"Trends in student subject choices are fluid and can change from year-to-year and over time.
"Some of the reasons behind these shifts include student interest, employer demands, international trends, teacher workforce changes and tertiary course requirements.
"When we see a significant drop in interest over a short period of time, we'll investigate and provide support where needed."
Cleaver said schools made decisions about which subjects to offer based on aspects such as teacher expertise and timetabling.
Subjects with low numbers could be offered through correspondence or combining enrolments with another local school.
John Paul College principal Patrick Walsh said technology, the arts and foreign languages tended to have smaller numbers.
"While we recognise the right of students to make choices around subjects and recognise chemistry, physics, biology, statistics and calculus are important we need students with well-rounded education."
John Paul College student Ashleigh Webb was one of only two Level 2 French students.
The school has a combined French class for Years 11 to 13.
"It's something I find interesting and it comes quite easily to me."
Ashleigh said she wasn't surprised there were low numbers at NCEA French as it became difficult and a lot of her friends had chosen to take the three sciences.
She said learning a second language was a good way to learn about other cultures and she planned to take Level 3 and scholarship French next year.
"You learn a lot more about the world ... it really feels like there's a lot more options for the future."
Rotorua Boys' High School principal Chris Grinter said external exam numbers didn't necessarily reflect subject participation.
"NCEA subjects can have internally assessed components.
"Small class sizes are always a challenge for schools from a staffing perspective, but in the main, we do not have a major issue with small class sizes."
Grinter said one of the subjects with low numbers at the school was Chinese. Nine students sat the Level 1 external exam.
NCEA exams began on November 7 and ran until November 30. Over the exam period there were 104 exam sessions. In that time 2235 Rotorua students would have sat an exam.
