The Educational Institute of Scotland says that before any changes take place, other steps will be necessary such as tackling the overcrowded curriculum, challenging narrow target-setting and reducing assessment.
The EIS's comments on the curriculum, submitted to the Scottish Executive as part of the national education debate, also recognise that the subject-based curriculum presents "hurdles to learning". Pupils have difficulty making connections between what is taught in different subjects at different points in the day, it states. But it stops short of calling for subjects to disappear.
The union says a future curriculum should be shaped by the aptitudes and skills pupils should be expected to acquire. These would include encouraging a commitment to learning, developing a sense of social responsibility, making decisions, being sensitive to others and acting creatively.
It insists that no reforms will be possible without smaller classes and backs a limit of 20 right the way through from P1-S6 as an "objective", with further reductions for practical and composite classes.
The institute's submission points to the increasing demands that schools must become more democratic for pupils and says this must be true for teachers as well, with a collegiate approach based on an "ethos of trust".