Subject-specific further reading.

These original lessons introduce the topic. The resources below offer additional information from educational institutions or public agencies. They did not review or endorse this site. Educators should select individual pages appropriate to learners’ ages.

• USGS Water Science School: water cycle

  Water storage, movement, and relationships with land use.

• USGS: finding your way with map and compass

  Map scale, topographic features, orientation, and distance.

Using an external source responsibly

Check the page’s author, date, purpose, and evidence. Record the exact page you use rather than citing an organization’s homepage. Separate direct observations, reported findings, and your own interpretations. External websites have their own privacy practices and usage terms.