Options could include grouping small primaries under a single head, better deployment of technology and classroom assistants, and using the best teachers to reach more children, according to TTA chief executive Anthea Millett.
Her comments came as official figures were expected today to reveal a further increase in job vacancies and in classes with more than 30 pupils.
Speaking at the launch of the TTA's corporate plan, Ms Millett said that the shortage of trainees and primary heads meant current recruitment drives could amount to "simply putting our collective finger in the dam".
Meeting the shortage of specialist secondary teachers would mean recruiting half this year's maths graduates and 40 per cent of English graduates into teaching.
Today's figures show a small increase in the 500,000 infants taught in classes over 30 - a legacy of the final Tory Budget which set schools spending for this year.
Schools minister Stephen Byers was expected to repeat Labour's pledge to end infant classes with more than 30 pupils by September 2001 and point to the pound;62 million already granted for extra teachers and classrooms.
Training league tables, page 6