Not the best idea!

So earlier in the year, my fellow art teachers were told to come up with an assessment for students to determine if they are showing growth in art.  We came up with a self portrait.  Everyone from Kindergarten to 5th grade was going to do a self portrait at the beginning of the year and then again at the end of the year to determine if they have grown as artist.  Not a bad idea until I implemented it today.  I was not here at the very beginning of the year when they drew the initial portrait, but I came back in October and reviewed their work.  Pretty typical stuff.  This week in the rotation I am doing the post assessment.  Students are drawing self portraits.  Directions are simple, materials are minimal, but the concept seems to be blowing kids away!  They want me to spell everything out for them and tell them exactly what to draw.  I don't do this so I don't know why they are doing this now.  Most of them only want to spend 15 or 20 minutes on it.  We were told we did not need to do the assessment this year which is great, but I thought it would be helpful.  An informal test for me to reflect on what they learned this year and what I can make sure I cover next year as the curriculum changes.  An opportunity for the kids to "WOW" me with their ability.
I will say I have seen some really neat self-portraits.  Maybe that is what I should take away from this more than anything.  Always look for the positive.