We spent about 30-40 mins on these, but the younger students lost focus more quickly than the older ones while initially creating their artworks. I thought that they would be completely done with it, but to my surprise during free art sessions they asked to continue working on them. With this in mind I would suggest doing this artwork in short bursts, as an activity for those who finish other projects early.
Below I've included a close up and far away image of each artwork to give a sense of how their appearance changes from each viewpoint.
This artist did a great job in spacing dots to create highlights in the hair and on the lips.
This artist had fairly even spacing throughout, but nonetheless, I like the resulting 'sunburn' effect.
The use of different sized dots on the lips and face in this image creates a very cool effect when viewed from far away.