Research evidenc on the value of homework:
From Review of studies on homework
by Caroline Sharp here
There is a positive relationship between time spent on homework and achievement at secondary school level (especially for older secondary students). Evidence at primary school level is inconclusive, because fewer studies have been carried out at primary level and results have been inconsistent.
Time spent on homework explains only a small amount of the variance in pupils' achievement scores, even at secondary level.
Studies conducted in the USA indicate that among younger (primary-age) children, lower achievers spend longer on homework.
And
The limited research into pupils' preferences indicates that pupils dislike being set routine homework tasks (such as finishing off classwork) which do not contribute to their learning. They prefer interesting, challenging and varied tasks that are clearly defined and have adequate deadlines.
Pupils' attitudes to homework appear to be related to characteristics such as age and cultural background. Several recent studies show that girls are more willing to spend time on homework than are boys.
There are contradictory findings regarding the relationship between amount of homework and pupil attitudes.
The suggestion that setting homework for primary-age pupils instills positive attitudes towards studying has received very little attention in the research literature.