Lesson Plans for Teachers

Sand Explorations

Materials:

• copy of outline map of Maui
• labeled Maui map as a control (from the phone book)
• sand samples from different beaches around Maui, labeled with location
• plastic spoons
• glue
• shallow glass dishes (one for each sand sample)
• white vinegar in a squeeze bottle

Before you begin:
Gather sand samples from 3-4 locations around Maui. Try to gather samples from leeward and windward beaches. Gather at least one sample from a "black sand" beach (such as Waianapanapa State Beach). If possible, gather a sample from a submerged area of the beach, one that remains underwater even at low tide (this sample will need to be well-drained before being used in the activity). Label the samples with the name of the beach they came from.

Background Information:
The first thing we come in contact with as we approach the sea from land is the sand. We lay on it, dig in it and often take it home with us in our clothes and swimsuits. But what is sand and where does it come from? How is a sandy beach formed?

Pick up a handful of sand and look closely. Depending on where it came from, you may see stones, coral rubble, bits of shell and other animal remains, the odd cigarette butt, and maybe small pieces of lava rock. Sand here in Maui can range from white to black with countless variations in between. Why do our beaches look so differently from each other?

A beach is formed from the interaction of land and sea. Topsoil may be blown and washed down from upland regions, particularly when the land near the sea is very steep or near disturbed agricultural areas. The power of wind, rain and wave pounding on a shoreline continue to break down our volcanic islands and return them to the sea. this same wave action, sometimes amplified by storms, breaks down coral reefs and grinds the coral rubble into smaller and smaller pieces. The shells and body parts of marine animals and rubbish from humans (broken glass, styrofoam, etc.) also add to the mixture we call sand.

Sand varies not only in composition but in texture. Fine sand is found on beaches where particles have been ground down over a very long period of time by continuous and gentle wave action. Some beaches with a large soil component to the sand have very fine, almost powdery sand. Beaches that are exposed to vigorous wave action or repeated violent storms often have more coarse sand. The texture of sand on a single beach changes as you move from surf line to the upper beach and from the top layer to the deepest layers.

Think about this...What changes in the texture of sand do you observe from the surf zone to the high beach? Do you observe "pockets" or concentrated areas of different textured sand as you walk along the beach? What do you think causes these differences in the size of sand particles?

In these activities, you will examine sand samples from a variety of locations around Maui and create a sand map. Based on your observations of sand samples and knowledge of the physical characteristics of the beaches they were gathered from, you will suggest at least one contributing factor for the formation of each beach sample. Using a weak acid (vinegar), you will test the samples to determine which have a high composition of marine-based components.