6. what objectives, principles and teaching techniques are used in education to improve the clean water & sanitation around the world?

"pacesetter of the south," comma inside the quotes

The peak above is part of the  sierra madre occidentals ,  a chain of volcanic mountains that runs through the middle of central america. 

Humans have survived and thrived in mexico city by using technology to create greater access to land. when the spanish conquered the aztec capital, tenochtitlan, in the 16th century, they built mexico city by draining the lakes and filling in the lake water to create more arable land for agriculture. this technique of land reclamation has continued to be fundamental to human civilization in mexico city.