I have used a great resource from natcoll/yoobee for a number of years now for students to learn PHP. This year I plan something different. Codeacademy has just released there PHP course.
I plan for the students to work on this for 10 periods. I hope this will given them enough of an idea around PHP to be able to confidently use it when we start working with wordpress a bit more.
I have started the course myself to be able to gain an understanding of what challenges that they will face, the first lot of exercises is more around understanding what the syntax of php is and how it is to be used within HTML tags. For me, it was remembering that at the end of a php statement it finishes with a ";"
UPDATE: Although the interface works, it is slow and sometimes you have to wait a couple of minutes before it will show up with a success or failure. There are a number of forum posts around this, and they seem to be working on the issue, but I can see this being a barrier to the students.
There does seem to be a number of issues facing us with this environment at present, feedback is slow or non existent on a number of the submissions. There is a constant Disconnect showing in the Console. The students started off so well, are now feeling disconnected and frustrated.
This is a common comment in the forum, its not just us. It could be to do with the new interface that they have launched.