I tend to put some of my best student work on my blog....I think most of us do that. However, like you....some of my students struggle to follow directions, complete tasks, or give me their best work. Aren't we all like that from time to time?
So how do we motivate the student that is not meeting grade level expectations?
PATIENCE is a big thing! At the end of the school year...I know it can be in short supply. Many of our children need to be loved & encouraged through the struggles. Sometimes those struggles are not reflective of their feelings/abilities for art...but go deeper into personal/home life issues. Not that we need to make excuses...but have understanding.
Next...don't let them get away with it! Call them out on what they are doing wrong. They won't grow if they don't know...or aren't made aware that you expect more from them.
Spend time with them...set down and work beside them with one of your examples. Model good artist behavior...model good craftmanship. Things like this are better caught than taught. They "catch" you doing the right thing...they may try to "copy" that behavior!!
Not long now...you can do it!!! Help your kids finish out strong!!