It is not known how or when the trace is placed upon a child, though it may be assumed that it begins either when the child begins to show magical talent or when they first go through the barrier to Platform 9¾. The Ministry seemingly ignores the trace during the school year as students at Hogwarts are expected to perform magic and are under the supervision of teachers. This 'blind eye' also seems to be extended to places such as Diagon Alley, Platform 9¾, the Hogwarts Express and the village of Hogsmeade (the only settlement in Britain inhabited solely by wizards and other magical beings) which is located close to Hogwarts and which 3rd year students and above can visit on weekends provided they have a signed permission slip from their parent or guardian. The Ministry also seems to turn a blind eye to the use of magic in the muggle-world when the child is under the age of 11 as their powers have generally not been developed enough to cause a problem, with a number of witches and wizards, including Harry Potter, Hermione Granger, Lily Evans and Severus Snape all known to have performed some under-age magic while growing up in the muggle-world that went unpunished.