New AFL Teaching Toy

I've been thinking recently about how to improve my assessment, and particularly how to make sure that students have actually done something with the scrawly bits of purple ink I leave on their work, rather than just looking at the grade and filing the rest under "sooo not bothered"!
 
I picked up some ideas from this excellent blog post on marking, and now have a new system:

1. When students complete their work, I get them to peer assess each other's work (where possible), writing comments in green ink.
2. I then take in the work and add my marks and comments in purple ink.
3. Once I've handed it back, the students are then given a specific prep task to add improvements or corrections based on my what went well/even better if comments. They do this using red ink.
4. Finally I check these corrections, and if I think they've done enough to go up a grade, they get a purple stamp using my new toy, fresh from Amazon.

 
I also record the improved grade in my mark book, and it counts towards their term grades.

I've only been using the green-purple-red-purple system for a couple of weeks, but my AS class have responded to it very positively. I'm sure the offer of an improved grade helps! It's been an excellent way of starting a dialogue with students about how they think they've improved and where there might still be gaps in their understanding: for example, today I've realised that one EAL student is confusing a "thesis statement" in an essay with an "atheist statement". Definitely something I will now spend some time clearing up next lesson.

I'd be keen to hear any thoughts on my new system, or what systems you have worked for you in your marking and AFL?