I am an editor of a popular scientific magazine Delta [webpage, in Polish only]. Delta targets high school and university students interested in Mathematics, Physics, Computer Science and Astronomy. I also wrote a few articles there [article list, again in Polish only]. You can also find my talks for high school students on YouTube [talk 1, talk 2]. If you have an interesting article for this audience please feel free to contact me! Even though Delta is published in Polish, you can submit articles in English and the editorial board will translate them.