As it is, when we had to teach them HTML, the resources we were given were using PHP at the same time, so I scrapped that and just taught them HTML myself. We never teach more than one concept at a time, so I don't know how these other things found their way into the curriculum/resources.
P.S. as a teacher, I can tell you I have seen students who even struggle to write pseudo code. It's like trying to teach them Greek (not all students, but some, and we need to cater to the lowest common denominator).
I hate having to cater to the lowest common denominator, I had to struggle with un-engaging classes all throughout elementary and middle school. I've seriously thought about becoming a teacher so I'd like to ask, in your experience, what happens to the children that are able to process more advanced information? Can something be done to keep them engaged and nurture their development too?
Oh definitely! Different students have different learning styles - some learn by memorising rules (ROTE), some learn by understanding the rules (Constructivist), some are visual learners, some are better at learning in group activities, etc. - and we have to cater to them ALL, to keep them all engaged (here's WHY we have this rule, here's a video about it, here's a group activity about it, here's a worksheet to practise it). But I was referring to the TOOLS that we use with class. We can't use a tool that the advanced students have no trouble with but the less adept students struggle with - we have to use a tool that the whole class can use, and that's what I meant about catering to the lowest common denominator.
Also some (not all) schools have special classes for gifted and talented (G&T) students. And in fact one class I've had in my time is a class which was comprised of half the students had various learning difficulties (such as being dyslexic), though they weren't told that (these days it's all about trying to keep them in the mainstream as much as possible. So in this class the dyslexic student had a regular student sitting next to him for immediate help with reading anything, which left me free to only need to help him with actual educational issues).
Oh! I just remembered this video. If you wanna know how students can struggle with pseudo code, watch the video. I use this video when I teach algorithms (students are even worse at that than pseudo code).