Secrets in a Grain of Sand
Lesson Plan by Greg McBride
Problem: What can we learn by examining the sand on a beach?
Once the materials listed above are assembled they can be kept in a dedicated container, ready for immediate use with little or no preparation time.
A great deal of information about a coastal region can be gleaned from an examination of the sand on its beaches. Here are some generalizations that may be helpful. The more sand is rounded the longer it has been exposed to significant current and wave action. The larger the average grains of sand are on a beach, the greater the wave energy on that beach at some time during the year. Fine sand can not exist where huge waves wash sediment away. Large rocks do not stay exposed if gentle waves carry fine sand in to cover them up. When keying out minerals that make up sand one can usually assume that the soft minerals are absent do to the destructive forces of currents and waves: only the hard minerals need be considered. Vinegar makes shell; coral and bone bubble so they are easy to tell from white mineral. A strong magnet clearly distinguishes magnetite from other dark minerals.
Each three-person team receives three sand samples. Or each team is responsible for getting three of their own labeled sand samples. One team member uses the key to identify all of the minerals in the sand sample. Another student uses the maps to find out what mountains, rivers and currents brought the sand sample to the beach where it was collected. And the third member determines the size and angularity of the sand.
Observe students conducting the investigation and grade their data/observation sheets.
Evaluate their presentation of findings to the class.
Students can be given a quiz on generalizations they can now make about characteristics of beach sediments.
Students can be given an unknown sand sample an correctly identify from a limited number of choices, where the sand came from and why.
Sand is the main ingredient. The sand can come from any beach, river or lake. It is important that the place where the sand was collected and the season be labeled on each sample. Sand can be kept in any container. The easiest collecting containers seem to be empty film canisters. For sand storage I like to seal the sand in a small, clear petri dish with silicon. This allows the sand to be examined with a magnifying glass or dissecting scope without taking out loose sand.
Other helpful equipment
Permanent sand slides can be made by placing a drop of white glue on one slide, pressing another slide onto the glue, dropping the desired sand samples on each of the two slides with a circle of wet glue each.
Temporary, perfectly serviceable slides, can be made by pressing the sticky side of clear tape on a sand sample and observing them sand side up.
Examine problems of sand erosion, as is seen on the outer banks of the Carolinas, or sand deposition, as is seen in most harbors. Ask students to brainstorm solutions.
Correlate sand types with the organisms that live in them. Consider special adaptations of sand dwelling plants and animals, and how those may have evolved.