http://webs.bcp.org/sites/vcleary/modernworldhistorytextbook/imperialism/section_3/turningpoint1.html - Modern World History provides an overarching summary of the Spanish and European expansions into the Americas.
https://www.britannica.com/topic/Mapuche - This Encyclopedia Britannica entry describes the Mapuche people of modern-day Chile and Argentina. It explains their history in the region, resistance to Spanish conquerors, and contemporary struggles.
https://www.youtube.com/watch?v=pFdiX8mj0Es – TED-Ed video sharing the story of the Magellan circumnavigation voyage.
https://www.youtube.com/watch?v=pLijVYVDKlc – Khan Academy explores the Colombian exchange of food, animals, diseases, and more. The significance of the exchange and the uneven consequences of germs spreading are explained.