A Feedback Idea that Didn't Stick
Last year, I tried giving feedback to pupils  about their homework  using a detailed marking scheme, highlighted to show successes and failures. A pupil's feedback would look something like this:
Question

Step

Comment

1a

differentiate sin to cos
 
use the chain rule to produce an extra multiplier of 2 (the derivative of the function inside sin)
 
keep 3 as a multiplier of the derivative
 
know to evaluate f’ at x=0
 
perform evaluation correctly
 
1b

realise that rearranging to tan(x)=... is the first step
 
take square root to give tan(x)=...
 
remember to use +/ square roots
 
find building block angle from exact values
 
choose correct quadrants for solutions
 
not available, as you did not consider other solutions
 
state solution clearly

My hope was that the pupils would use the feedback to see where they had "gone right" as well as where they had gone wrong, and would be able to use it to help with corrections.
As it turned out, these feedback forms (returned to them electronically via the maths department Moodle installation) were time consuming to complete, and hard for pupils to interpret. Some of the youngsters in my Higher class found them very useful, but most didn't, and the forms didn't have any impact on the quantity or quality of corrections being done.
You win some you lose some! I guess this idea might work for someone else in a different situation.