Litter includes many items, from wrappers and cans to banana skins and complete bags of rubbish. But dog faeces are refuse, not litter, and are subject to separate regulation. Natural matter, such as leaves, is also refuse rather than litter.
Details of what schools must do to comply with their cleansing responsibilities are contained in a code of practice on litter and refuse.
Local authorities place schools in zones, which have grades for cleanliness, and standards for the speed expected to return the area to a litter-free state.
Schools must comply with these, but can take some comfort from the fact that the code emphasises the importance of the high standard of cleanliness, rather than how often the school is cleaned up.
Grade A is "litter-free"; grade B - not much litter apart from small items; C - a lot of litter with small build-ups; D - a lot of litter with large build-ups.
Normally 24 hours is allowed for the school to improve the situation, up to a grade B or A.
Those who drop litter are criminals and are liable to fines of up to pound;2,500. Heads, too, can be embarrassed, since any citizen, including pupils, can take legal action against the school to get litter removed, if the litter falls below standard for longer than allowed.
Ultimately a local authority could declare the school a "litter control area" if it cannot achieve a reasonable standard in the time allowed.
The school is then issued with a "litter abatement notice".
So it pays to keep up the good fight!