Why should you tell your pupil to obey the speed limit shown on this sign?

Explanation: Stone chippings are often used to finish off a new road surface. They may take several days to bed into the tar underneath. Advisory speed limits are used to help reduce the amount of chippings thrown up by passing vehicles. Chippings can cause damage to vehicles and other road users - especially cyclists, pedestrians and horse riders. There's also an increased risk of skidding on the loose surface.

Category: Band 2 traffic signs and signals

References: Highway Code: Page 113, Know Your Traffic Signs: Page 137