What are the best sustainability projects for primary and secondary school students?

Tens of millions of students in secondary schools do interesting school projects as part of their studies. Just imagine if a good portion of these were related to cleantech and sustainability. What are some of the interesting sustainability projects that can be done by primary and secondary school children?

How will it have a positive impact?

Putting Humans in Better Control of Planet Health

Who will it have a positive impact on?

Children