You don't get better thinking from a student then when they are taking a test. Even if they miss the problem - they probably thought hard about it and really made their best attempt. So after the test it is very beneficial to go over the exam with the students...but who has the time??? There is more material to cover and barely enough time for that. My solution - make a video of myself working the key. I always provide a copy of the key to my exams to the students - now I use my tablet, OneNote, and Camtasia to record myself working through the key so the students can see a step by step demonstration of each problem. After I have made the video I select "publish as pdf" under the file option in oneNote and wahlah the students have both a hard copy and a video copy of the key. I gave my college algebra students an extra credit opportunity where they had to watch the video and then email me 3 questions that they missed and describe what the did wrong - this was very beneficial...the students loved being able to hear and see me working the problems.
Here is an example of what I did.
Discussions and discoveries about using tablet laptops for online and face to face instruction at McLennan Community College.