Learners learn that dams do not last forever. Similar to other human-made structures, such as roads and bridges, dams require regular maintenance and have a finite lifespan. Many dams built during the 1930-70s, an era of intensive dam...

Anna Komnene, daughter of Byzantine emperor Alexios, spent the last decade of her life creating a 500-page history of her father's reign called "The Alexiad." As a princess writing about her own family, she had to balance her loyalty to...

[Free Registration/Login may be required to access all resource tools.] Describes the range of habitats that prokaryotes occupy.