The paths that water can take through Earth's systems are many and complex. Examine the following diagram from NASA depicting the water cycle. Studying the water cycle is important because changes in the water cycle affect all parts of the Earth system. Background information and teaching tips are provided.

Scientists study ice sheets because they influence weather and climate, playing a role in atmospheric and ocean circulation. Ice sheets can also have huge impacts on global sea levels because they store so much water. Explore this four-part media gallery of visualizations, data, animation, and video from NASA showing changes in the Greenland Ice Sheet. Resources include background information, a student handout, and teaching tips. Closed caption available.

Help Rozalia clean her Pizzeria kitchen by using different methods to sort out mixtures.

Psychology is designed to meet scope and sequence requirements for the single-semester introduction to psychology course. The book offers a comprehensive treatment of core concepts, grounded in both classic studies and current and emerging research. The text also includes coverage of the DSM-5 in examinations of psychological disorders. Psychology incorporates discussions that reflect the diversity within the discipline, as well as the diversity of cultures and communities across the globe.Senior Contributing AuthorsRose M. Spielman, Formerly of Quinnipiac UniversityContributing AuthorsKathryn Dumper, Bainbridge State CollegeWilliam Jenkins, Mercer UniversityArlene Lacombe, Saint Joseph's UniversityMarilyn Lovett, Livingstone CollegeMarion Perlmutter, University of Michigan

By the end of this section, you will be able to:

Describe the assumptions of the psychodynamic perspective on personality development
Define and describe the nature and function of the id, ego, and superego
Define and describe the defense mechanisms
Define and describe the psychosexual stages of personality development