How to list activities done before 9th grade if at all?

My middle had a long lasting competition where the entire grade competed to send an experiment to the International Space Station. Among 60 groups we won and over the summer after eight grade we spent hours putting it together and sending it off to SpaceX. I want to include this in my application as it relates to my potential engineer major and I don’t have other activities that I can replace it with. Any help as to the best way to do so is much appreciated. Thanks!

Hello, maybe talk about it in one of your essays and how it sparked your passion for engineering.