Not much of an artist, but this might help...

I really enjoyed playing with Google Drawing. I'm not much of an artist when it comes to physically drawing something, but computer apps that do it are wonderful. Drawing works a lot like the generic "paint" program that comes on most computers. Many of the mouse functions as well as the shape and drawing manipulations are similar, if not identical. I simply drew a few lines, made a square, an arrow, imported a picture, and added a text box just to get a feel for the different options with Drawing. I looked at the middle school lesson plan before I actually experimented with Drawing and was totally lost. Then I explored and the Tangram plan looks like a lot of fun for students (and teachers). Learning to manipulate and understand shapes will be made easier through Drawing and the collaborative aspect is just another bonus (as it has been in with all of the Google Drive functions).
Drawing never seemed to be something useful for subjects other than art until I read the handout. The reading and writing assistance that it explained was so obvious (afterward) that I felt a little foolish for not seeing it. Though the handout suggested there are further math applications than geometry, I will need more time to see if that's the best option. Obviously, the collaborative aspect makes most of the Google Drive functions exceedingly more useful so maybe there is more in it than I understand after the little bit of playing I have done with Google Drawing.