Cos'è più importante dell'ossigeno ?

Follow the blue arrows ! ;-)



http://en.m.wikipedia.org/wiki/File:Photosynthesis.gif


Teacher Q: 'Is there anything more important than oxygen?'
Studenti A: 'Trees!'


Tree poems
http://www.ncsu.edu/project/treesofstrength/poems.htm
Some thanks for every lovely tree.