Hour of Code
Code.org is the non-profit organization behind the initiative to show that anybody can learn the basics of computer science, and give every student at least one Hour of Code.
One-hour tutorials are available in over 40 languages and is suitable for all ages.
The global movement reaches tens of millions of students in over 180 countries.
It's free to join in, both as a student and as an organizer.
Last time I checked there were 162 748 Hour of Code events planned around the world.
The main event takes place during December 7-13, but anyone can host an Hour of Code anytime and anywhere. They've chosen that date because it coincides with Computer Science Education Week.
You can find the tutorials here. They are clearly marked with suggested age categories, and all have different themes. For the younger students there are for example Star Wars, Minecraft and Frozen to choose from.
Don't have devices or internet at your school or usergroup? No problem, they have even thought of that with their series of unplugged computer science material.
The suggested age range is 4-104 years.
I think it's a fantastic initiative, and our usergroup Coding After Work is naturally participating.