CLILing two birds?

To be honest, I've often been a bit sceptical about the value of CLIL (Content and Language Integrated Learning). The idea that languages are best learnt when the focus is on something else (ie Science, Maths, PE or music etc) is an attractive one, but is there a danger that, rather than killing two birds with one stone, neither the content or the language gets learnt and learners end up leaving the lesson with nothing?My scepticism partly stems back to a summer course on CLIL I was leading for 30 Spanish primary school teachers a few years ago. The teachers on the course had suddenly been informed that from September they would have to teach their subjects in English, rather than Spanish, and most of them were not happy about this at all!The were two main reasons for their concerns. Firstly, many of them felt that their own level of English wasn't high enough to be able to do this. How could they teach Science in English when they didn't have a large enough science vocabulary themselves, or an appropriate  level of spoken fluency?Secondly, they were concerned that if they taught Science in English to young learners it would be at the expense of developing a Science vocabulary in Spanish, and knowing how to talk about Science in Spanish was important of course since the children lived in Spain.In the video below you can see me doing a HUP online session with a group of eighteen, 15 year old girls in a Ministry of Education school in Hebron, Palestine. They are on the Scientific stream, but they are not studying Science in their regular classes in English, they're doing it in Arabic. However what we are doing in this session is, in my opinion, a form of  CLIL, and I think the problems that the Spanish teachers identified in their own context aren't really an issue here.For a start their teacher, Nabiha, is an English teacher not a Science teacher and, like most Palestinian English teachers she has a very advanced vocabulary in English and an excellent level of spoken fluency.Also, these students are older and have already developed a Science vocabulary in  Arabic. The learning happens when they try, with support from their teacher and from me, to reformulate this into English. And it's interesting to me that they are also taking on the role of teacher. I was rubbish at Science at school and I'm actually learning about Science myself through the questions they ask me.What do you think?https://youtu.be/7_C82IdjrDc