Most of the class are "determined realists". Some are "comfort seekers" and a couple are "short-term conformists".
Teachers will give teenagers better advice on course decisions if they slot them into a "mindset" category, according to research funded by the Department for Education and Skills.
The research suggests that most students fit one of eight categories when they decide which subjects they want to take at the ages of 14 and 16.
The categories were developed by SHM, a consultancy in London, which interviewed Year 9 and Year 11 pupils in six schools.
It found that the way students made decisions varied according to factors including how optimistic they were, how clearly they viewed their future, how willing they were to take risks and go to new places, and whether they felt that success was a result of hard work or luck.
The most common type of teenager appears to be the "determined realist", who has a firm idea of the job they would like to do. One, who wished to be a mechanic, said: "There's no point learning about history or Buddhism - that won't let you change a camshaft."
Also common are the "comfort-seeker" and the "short-term conformist". Both groups have little clear idea of what they should do in the future.
The rarest type, the "unrealistic dreamer", are optimistic children who believe their success will be down to luck. The research suggests that teachers and career advisers should adapt the way they work with these pupils.
"Determined realists" could benefit from detailed advice about overcoming specific obstacles between them and their chosen careers, while pessimistic "defeated copers" might gain more from a boost to self-confidence.
A parallel study by the National Foundation for Educational Research agreed that schools should provide more personalised advice for pupils and take their mindsets into account.
However, it noted that pupils' mindsets often changed over time and could be influenced by their schools. A quarter of the 165 students that the NFER team followed could not be placed in one of the eight categories.
Alan Vincent, general secretary of the Association for Careers Education and Guidance, said the new attitude categories would be very helpful to teachers.
He said: "We don't want to stunt students' ambitions. The world is full of anecdotes about successful people who were told by their schools they would never achieve in their careers.
"But you do sometimes meet young people whose expectations are totally unrealistic, such as becoming a sports professional when they have shown no aptitude. You have to gently explain the reality and suggest alternative jobs they might enjoy."
Mindset Profiles and How Do Young People Make Choices at 14 and 16? are available at www.dfes.gov.uk
"I know what I want to do - let me focus on that." Has a clear picture and is optimistic.
"I'd like a nice life." No clear picture, prefers to stay with the familiar.
"What's the next step in the educational system?" No clear picture, optimistic.
"School, degree, masters, get rich (not sure doing what)." No clear picture, believes success is a result of hard work.
"I'll make do with what I can do." Pessimistic, believes that success is a result of hard work.
"My ambition will get me there." No clear picture, optimistic.
"How can I decide? It's all too much." No clear picture, anxious.
"Yeah, I'm going to be a surgeon. Or a deep-sea diver." Optimistic and believes success is a result of luck.