Yes. On average, the Forest Service updates its maps every 2 to 7 years. For some maps where little change occurs, revision may not be scheduled for many years. 
The USGS does not have any positions specifically targeted to teachers, but appropriate positions do exist.
The following USGS products will be helpful in determining the background levels of various elements in soils and other surficial materials:
The USGS Publications Warehouse provides an online catalog where you can place orders, view price information, download scanned versions and view a list of recent publications.
Bioremediation is the process by which microbes (generally bacteria) or plants transform a harmful water contaminant into a non-harmful substance, much as we turn sugar into carbon dioxide
Landsat 8 carries two push-broom instruments: the Operational Land Imager (OLI), and the Thermal Infrared Sensor (TIRS).
It is not an easy task to keep a swimming pool so clear and clean. If you just set a pan of water outdoors in the middle of summer, you'll see that it ends up containing gunk very quickly.
Of the 1,740,000 metric tons of silver discovered to date, 55% is found in just four countries on earth. All the silver discovered thus far would fit in a cube 55 meters on a side. 
Gas hydrates are a crystalline solid formed of water and gas.
Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by ground water circulating through them. As the rock dissolves, spaces and caverns develop underground.