Thousands of schools in the UK are taking part in a science experiment with astronaut Tim Peake.
Pupils have been sent seeds, of the salad leaf rocket, that have been on the International Space Station for six months.
They'll be comparing them with seeds that haven't been in space to see if there are any differences in how they grow.
One of the biggest challenges with living in space is how to feed people without the need for regular supplies being sent from Earth.
The results of this experiment could help scientists to try and find a solution.
Jenny visits a school that's been busy planting...