First, sea spray and wind carries salt onto the surface of the already frozen ice making it salty, and, secondly, sometimes the ice freezes so quickly that pockets of salt water are encapsulated in the fresh ice later to freeze making the whole body of the ice salty to taste.- see what your students come up with. TEA Charlotte Kelchner adds that when ice forms it is slightly concave towards the center of the floe thus trapping and freezing and spray that comes onto the floe. Also, she continues, sea ice is constantly moving causing pressure ridges and depressions which scoop up or splash up large quantities of sea water onto the floes. Discriminate between sea ice and icebergs. Icebergs are the floating remnants of glaciers which have calved into the sea and they contain fresh water only having formed on the continent.
Teacher can assess the quality of work on the worksheet and the lab report.
A first person report on the Jeannette expedition can be included in a portfolio document which may also include the lab report, the worksheet and other art work . Some writing about the Heroic Age is requisite in the portfolio. Additional work and research that may be included in an authentic assessment mode might include an essay with maps about why DeLong may have thought that the Kuroshio current would have carried him to the pole. Map work showing the extent of the Arctic and Antarctic ice sheets , including data from this year and last would be of interest. Authors Larry Rose, Science Teacher, TEA Associate, Pleasanton Middle School, Pleasanton, California Mail to Larry .