How much magic can children do before they go to school? – Starting Harry Potter https://www.startingharrypotter.com/explore/questions/how-much-magic-can-children-do-before-they-go-to-school
To get into Hogwarts you must have the ability to produce magic. Obviously, children don’t use a wand until they attend school – so young witches and wizards demonstrate they are magical by doing something accidentally, often when scared or angry.
Finally, when Dudley thumped Harry in front of the snake in the reptile house at the zoo, the glass vanished
