Ms Morris will argue the move will free qualified people to spend more time on planning lessons, tailoring them more closely to children's individual abilities.
In a speech to the Social Market Foundation, she will pledge to rip up traditional timetables and allow heads try flexibile methods of teaching.
Classroom assistants duties vary from taking registers to helping special needs children. Some train on the job to become qualified teachers. Under the plan they will be allowed to supervise pupils that has been set by a trained teacher. In some cases they could take over classes in a teacher's absence. They could also invigilate tests, give pastoral support to pupils, and give reading help.
There are 127,00 aides working in schools. The government argues teachers could delegate some of their responsibilities and expects to recruit another 20,000 assistants by 2006, plus 1,000 bursars to help head teachers with finance.
Pilot projects will be set up next year to try changes to the school day. Some schools may also be allowed to srap traditional once-a-week language lessons and replace them with a few intensive weeks of cramming languages during the summer holidays.
Secondary schools will also be encouraged to swap staff with universities, further education colleges, and the private sector. Ms Morris hopes visiting lecturers will encourage children to aspire to higher education.