Searching Sand

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Searching Sand

Grade Level: 5-8

Objective: To learn what sand reveals about the process of erosion.

Methods: Investigate a variety of sand types.

Materials:

[Note: Sand guide, data sheet and story sheet are PDF files. If you do not have the free Acrobat Reader, download it.]

Sand Guide

Sand samples*

Hand Lenses

Sand Data Sheet

Sand Story Sheet

*Note to teacher: You will need two samples of sand. For the first (Sample A), any sand sample collected along a river's edge will work. The higher the quartz content, the easier it will be for the students to identify. For the second (Sample B), any biotic sand containing shells, coral, etc. will do. These are most often collected along island beaches.

Time Needed: One to two class periods

Content Background: See About Sand

Assessment: Students complete the Sand Data and Sand Story Sheets

Brainstorm with your students:

What does sand look like?

What is sand made of?

Where do you find sand?

Where does sand come from?

Distribute sand samples:

Have students look at sand sample A and guide them in their observations by asking:

How do the grains differ from each other?

Is the sand a single color or many colors?

Is the sand all one thing or a mixture of many things?

Can you determine what the sand is composed of?

Are all grains the same size, texture or shape?

How can each of these differences be used to learn about the sand?

Where did the sand come from?

How did it get to where it was collected?

This can lead to a good review of the rock cycle and concepts of weathering, erosion, transport, and deposition (sedimentation). For instance, if the sand comes from rock fragments and minerals, how does the rock get broken up? (physical and chemical weathering) How do grains of sand get smooth and round? (mechanical abrasion during transport) Why is some sand large-grained or coarse? (less erosive processes or time) Why is some sand very fine-grained? (greater exposure to erosive processes or time) What do you think you can tell about the history of this sand? (parent material, weathering and transport processes, approximate age)

For the teacher:

Sample A was collected along the banks of a riverbed. It is completely abiotic in nature and is produced by the wearing down of different kinds of rocks and minerals. It is mostly quartz (clear grains) which is harder than other rocks, so it remains after softer rocks have eroded away. The grains are mostly rounded, smooth, and polished, indicating that it was eroded by water. It is fairly well sorted for size. Since sorting and rounding all take time, it has probably traveled some distance from its original source. Its origin is continental rock.

Now look at sand sample B. Compare it to sample A for angularity, sorting and grain size, color, texture and composition. How is it different?

For the teacher:

Sample B is mostly white in color with some pink. There are bits of shell and coral therefore the sand is mostly biotic in nature. This sand is not well sorted by size and the grains are angular and coarse and it is therefore of relatively recent origin. This sand has not traveled far and is therefore quite close to its origin. It is island sand.

Give students the Sand Guide and explain how to classify sand by it size, its composition, and its angularity. Remind them that the appearance of the sand can give us clues about its history. Their task will be to examine sand from different localities and to fill out a Sand Data Sheet for each different sample.

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updated February 6, 2002