Harry occasionally ran into the champions from the other schools in the castle.
Like Harry and Ron, all the champions from the other schools had stayed at Hogwarts. Unlike them, most of the other students from those schools had stayed at Hogwarts too.
Presumably, their schools had also set some requirements, hoping the other students would stay to help the champions solve the riddle of the Second Task's clue.
It was clear that none of them had solved the clue to the Second Task yet. Whenever Harry and the others ran into them in the castle, their brows were all furrowed, as though they were constantly thinking something over.
Harry could not help feeling secretly pleased, because they had already deciphered the clue to the Second Task.
Those three spells were specialized spells, intended specifically for use on large magical automata.
Magical automata were different from ordinary things. Since they needed to be powered by magic, their materials had spells placed on them. And those spells made it difficult for ordinary magic to work on them.
This was called magic interference, meaning the interference between different kinds of magic.
Although Professor McGonagall had not spelled it out, she might as well have. Even without Hermione's reminder, Harry and Ron would soon have worked out the key once they went back-at least, that was what the two of them thought.
Yet this single clue had four layers to it, even if the second layer was easy to figure out once they got past the first, and even if the third and fourth layers meant almost the same thing, with the fourth actually being a little simpler.
Still, Harry and Ron insisted that without a professor's help, even a proper seventh-year honors student would have struggled to solve the entire puzzle.
Hermione