I had a look at CodeMakr (www.codemakr.net)... promoted as free a few posts back by someone who has made 8 posts here.
It lets you have one lesson free... and then you have to BUY additional courses, if you want to proceed. And I couldn't find what those courses would cost.
It let's you program an Arduino!
Joking aside... for a hard pressed school, where they don't have someone on the staff who knows how to program, MAYBE this would be an answer to the idea that in secondary school "every child will learn two programming languages, one of them text based" (My recollection of something supposedly from Big Brother's manual of what every school must teach.)
If it gets kids using Arduinos, it can't be all bad!