And secondaries may have to consider lengthening the school day to allow for more project work.
Enthusiasm for projects in the classroom has waned since the 1980s because of the demands of the national curriculum.
But Qualifications and Curriculum Authority chief executive David Hargreaves said projects - particularly in design and technology - could be the best way to teach new knowledge and skills.
In a speech at London's Institute of Education, he said: "Many students need more opportunities to engage in parallel activities while still at schools, such as well-designed projects, especially where this is linked to some activity in the workplace or the community, rather than in school.
"It may entail a longer school day, as worthwhile projects are more difficult to design and implement successfully than traditional lessons."
Mr Hargreaves said design and technology was moving from the periphery of the school curriculum to its eart and would be at a premium in the so-called "knowledge" economy - where simple, manual jobs disappear and workers cannot expect jobs for life. Instead they will need a "portfolio" of skills and knowledge useful to many employers.
But he described as "premature and dangerous" the recommendation by Tom Bentley, director of the left-leaning think tank Demos, that the curriculum should be cut in half to allow students to concentrate on mastering new types of knowledge.
John Dunford, general secretary of the Secondary Heads Association, supported Mr Hargreaves's proposals.
He said: "When curriculum and assessment became politicised it militated against projects and coursework and as a result, schools lost an awful lot."
But Nigel de Gruchy, general secretary of the National Association of Schoolmasters Union of Women Teachers, said staffing ratios would have to increase substantially for projects to be effective.
"Teachers would revolt at the idea of lengthening the school day. More teachers than we currently have are needed to supervise and monitor this kind of work."