Hey! I am very interested in this question! kolia mentioned my Pluto.jl project, which is primarily designed for the undergraduate level. It does make programming and interactivity easier, but it does not provide anything exciting (graphics, games) on its own.
Pluto with Luxor might be nice for education, its author cormullion made this cool GIF. But Pluto’s interaction is always one-directional: sliders and buttons defined in different cells - it’s not a platform to make games 
At the school where I worked we had a lot of success with scratch! With more advanced students we started with python, with PyGame (also works online through repl.it, and students can share games with eachother), or by controlling a raspberry Pi. (also have a look at the micro:bit if you want to do electronics)
Minecraft Education edition looks exciting - there’s an in-game scratch-style programing language to control the world with. And this has a natural advancement to Julia: there is a Julia package PiCraft.jl to control the minecraft world using Julia. Less intuitive than the control-flow-language, but you can do more powerful things like fractals!