They spot lots of students from Hogwarts with their families, and they also see a bunch of unfamiliar teenagers – kids who go to other wizarding schools.
Harry had no idea that there were other wizarding schools (neither did we), but of course, it makes sense – Hogwarts can't be the only one.
Back at the tent, the rest of the Weasleys turn up: there's Fred, George, Bill, Charlie, and Percy all ready for lunch.
As they settle in to eat, Ludo Bagman comes by (Head of the Department of Magical Games and Sports – so he's in charge of the World Cup).
Ludo is looking excited about the upcoming match.
Ludo asks Mr. Weasley if he wants to make a bet on who will win.
The twins jump in and bet a huge amount of money (over 37 Galleons) that Ireland will win but Viktor Krum will get the Snitch. (For more on how this is possible, check out the section on scoring at the Harry Potter Lexicon)
Ludo accepts the bet, though he thinks it's a real long shot.
Mr. Weasley asks Ludo about that missing witch in his department, Bertha Jorkins.
Ludo doesn't seem too worried. She has a "memory like a leaky cauldron and no sense of direction. [...] She'll wander back into the office sometime in October, thinking it's still July" (7.123).
A "stiff, upright, elderly man" (7.126) approaches the party. He's about as different from relaxed, happy Ludo as a person can be.
This is Barty Crouch, Percy Weasley's boss at the Ministry.
Sucking up hugely, Percy asks Mr. Crouch if he would like a cup of tea.