However, what I have discovered is that my students can reflect well on their work, the important thing is a well-worded template or prompt that asks students to justify their work. If they are saying that their work was successful, they need to say why this was.
They also need to have a good understanding of our learning objectives - in short, where are we headed. When students understood what I wanted them to be doing (big picture wise) their reflections were deeper and more meaningful. For some students who think a bit more deeply it actually helped to have an authentic text to draw upon in their reflections. I recently experimented with giving students a text 'what makes a good artwork'. This was an interesting exercise but a bit rushed as this was at the end of time we were pushing to get artworks finished in time. Also I would need to search for a range of texts potentially so that this task was more accessible for different levels.