Encourage them to keep their planner up to date and be a good parent by signing it regularly and ensuring they tick off work as it is done.
Two out of three of mine get payback/detention if their planners aren't signed each week, so that definitely gets done!
Mine are very adept at forging signatures - not hard as OH's is an indistinguishable scrawl. My late father made a huge fuss about the principle of signing my homework diary every week, believing it to be my responsibility not his. This was in the 1970s so now I can see he was a bit of a rebel, despite being a senior police officer. Having been summoned to school to explain himself, he came to a gentleman's agreement with the head of lower school, who was approximately 3 feet shorter than he was, that 'a signature' would appear but that it wouldn't necessarily be a parental one. (You can see where I got it from, can't you?
) I am afraid I take the same stance with my own lot - as far as I am concerned homework is their business and my signing the damn planner just makes me
in some way responsible. So, if I happen to have a pen when they come with it, then I sign, otherwise 'a signature' appears. And everyone is happy.