NEXT CLASS IS ON 14.5. 2018. In the meantime, please work on your projects. You can consult them via e-mail.
Also, regarding the data tree, check this cool video out:
Other cool websites to look through:
https://naeimdesigntechnologies.wordpress.com/
http://atlv.org/education/grasshopper/
http://www.designcoding.net/category/hints/
http://www.giuliopiacentino.com/grasshopper-tools/
http://mkmra2.blogspot.cz/2016/03/working-with-meshes-in-rhino-and.html
http://www.grasshopper3d.com/profiles/blogs/marching-cubes-curve-wrapping-more-metaballs