Sandringham School in St Albans has made history by making the first amateur radio call from the UK to a British astronaut on the space station.
The children contacted Major Tim Peake as he flew overhead on Friday morning.
Pupil Jessica, who has recently passed her radio exams, led the conversation.
It took a few minutes for the crackle and hiss to die down and allow the students to put some questions to the astronaut, before the ISS then went over the horizon and out of range.
Jessica called it an "amazing experience" to be talking to someone 400km above them, but said the significance of the day's event had yet to sink in: "When I get home, I'll be completely in shock."
Her head teacher, Alan Gray, said it had been an extraordinary opportunity for the school.
"It's a way of inspiring young people into science and technology - seeing the opportunities that may be available to them," he told BBC School Report.
"What you're seeing is that space has an awful lot to offer. It's not just about talking to Tim Peake on the space station. There are many other things that are useful for young people and will help with their learning."
For a short period, it looked like the connection would not be made.
The radio equipment set up in the school hall was using a local dish and the famous Earth station at Goonhilly in Cornwall.
Jessica put out repeated calls with no response: "Golf Bravo One Sierra Sierra, GB1SS - this is Golf Bravo One Sierra Alpha November calling and standing by, over!"
But then through the crackle, Major Peake's voice could just about be heard. A bit of channel-switching soon improved matters, and the pupils raced to the microphone to put their questions to "Britain's man in space".
Imogen asked if liquid hydrocarbons would form balls in microgravity; Jess wanted to know how the astronauts studied alloys on the space station; and Jamie was puzzled about the behaviour of a helium balloon on the ISS. Major Peake just had time to tell the students that the balloon would not rise up like on Earth before he was again drowned out by the static.
The connection was all too short, but that did not dull the pupils' enthusiasm. "I want to be a spaceman when I grow up like Tim; it would be amazing!" said Philip.
The European Space Agency astronaut launched to the orbiting platform on 15 December and is due to stay aboard until June.
Other schools across the UK will get a similar opportunity to Sandringham in due course.
Major Peake has a big highlight coming next week when he will perform a spacewalk.
He and crewmate Tim Kopra will venture outside the ISS to replace a failed voltage regulator and restore the station to full power.
It has been operating without one of its eight power channels for a number of weeks.