Secrets in a Grain of Sand

Lesson Plan by Greg McBride

General Information:

Problem: What can we learn by examining the sand on a beach?
Time Allotment:  Each team member will require about two class periods to complete their investigation. Then the teams will need a class period to discuss their findings among themselves and for all teams to share their findings.

Objectives:

1. Intellectual – students will learn to use a variety of skills and an interdisciplinary approach to discover as much as they can rather than just trying to find a “right” answer.
   -Students will apply previous knowledge about geology, identifying minerals, erosion and weathering, ocean currents and waves, geography and map reading, in their study of sand.
2. Social -students will work in interdependent teams where each student does a part of the investigation and shares it with their team.
   -Students will depend on each other to bring a variety of sand from a variety of places to enrich the experience of all.
3. Personal -students will realize that they can use their own experience, skills and knowledge to investigate a habitat and learn without getting facts someone else discovered from a text.
   

Preparation

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.

Background Information

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.

Procedure

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.
The team members exchange jobs as each sand sample finished so that each person does each job once.
One the third day each team shares what they have learned with the class.

Assessment

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.

Materials

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.

• A demonstration of sand size vs. settling time can be made by putting 3-4 cm of sediment in a clear two liter plastic bottle and top it off with water and a cap. Place other sediments in two or three other plastic 2L. bottle. When you simulate a wave by shaking all of the bottles the one with the largest gravel sediment will settle faster than fine sand. And if one of your bottles has mud sediment from a slough it may not settle for days.
• Special sand sieves can be made by gluing screens of different sizes on 2cm wide slices of pvc pipe. Once students have samples of different grain sizes it is helpful to make and keep slides of each size for comparison with unknown samples.
• hand lenses or dissecting microscopes.
• maps which show the direction of prevailing currents near the beach each sand sample came from, and maps which show the main creeks and rivers which dump sediment into the sea and the source of each creek and river.
• a key to the minerals.
• sand particle size and angularity chart from a geology text.

Possible Extensions

1. Give students a challenge. Provide them with an unlabeled sand sample and ask them to try to determine where it came from based on its characteristics.
2. Add information to a local, state or world map by gluing sand samples on the map where the sand was collected. Ask students to try to figure out what features of the land and sea must be in a place they have never been just by examining the sand from that place.

Additional 
Show the old classic film – Beach, River of Sand

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.