The pilot project, in 18 authorities, follows a three-year stall in English scores for 11-year-olds.
Assistants taking part in the pilot are being given four days of training specifically aimed at supporting children in the run-up to the national tests in English and maths.
Dr Kevan Collins, who heads the Government's primary strategy, said assistants would focus on "borderline level 3level 4 children".
The project runs until Easter and will be evaluated by questionning the assistants, heads and children involved. It will also look at the projected test results for the children and their actual scores in the 2003 tests this May.