When it eventually explodes, the balloon would likely have stretched to a diameter of 20m, said Marius van Rijnsoever, who is helping organise the launch.
The second record would, of course, be dropping a teddy bear from that point in the atmosphere.
"It's going to take him about two hours to get up there — and then obviously coming down is going to be a bit quicker," said van Rijnsoever, whose daughter Amalia is a pupil at the school.
SpaceTeddy will be equipped with a special parachute for the descent, which would begin at speeds of around 120km/h, before slowing to 10km/h at the time of landing.
A mobile chase crew of school pupils — complete with computers and GPS trackers — would be waiting on the ground.
"We are just waiting for a clear day with a good wind direction that means teddy won't drown off the coast somewhere."
He pointed out the launch wouldn't just be a fun stunt, but a great opportunity to teach the kids about space and the ozone layer.
Every class had designed a paper airplane which would be released by the year 6 computer club "TeddyNauts" from their control centre once it was higher than 35km.
"The year 6 kids have also designed a science project to measure the ozone layer and have programmed a 'raspberry pi' computer to send data back from space to see how the ozone layer is recovering."