1.A.2. What Happens to Sand When You Build Or Dig in It?

Concepts: Simple physics of sand--the holding properties of sand, how circumference of a pit is dependent on the depth of sand, and animal adaptations for digging.
Skills: Cooperative learning, observation, scientific method, measurement, and discussion.
Time needed: Approximately 20 minutes for each part.
Best time of year: Anytime.
Sunshine State Standards: LA.B.2.2.1, LA.C.1.2.1, LA.C.1.2.5, LA.C.3.2.2, MA.A.1.2.3, MA.B.1.2.1, MA.B.1.2.2, MA.B.2.2.1, MA.B.2.2.2, MA.B.3.2.1, MA.E.1.2.1, MA.E.1.2.3, MA.E.2.2.2, MA.E.3.2.1, MA.E.3.2.2, SC.A.1.2.1, SC.B.1.2.1, SC.G.2.2.3, SC.H.1.2.1, SC.H.1.2.2, SC.H.1.2.3, SC.H.1.2.4, SC.H.1.2.5, SC.H.2.2.1, SC.H.3.2.2, SC.H.3.2.4, VA.A.1.2.1, VA.B.1.2.1

This activity has two parts that explore the shape-holding properties of sand on two very different scales. During Part One, students will make small dunes and see whether they are affected by the amount of sand. During Part Two, students will discover that the circumference of a pit at the surface of the sand is dependent on the depth of the pit.

1.A.2 Part One-Piles of Sand

This activity can be presented as a demonstration or you can divide your class into teams and guide them through.

Materials:
Each team of four students needs:

  • A cardboard box (any size) with the front panel cut out. (Note: When front of box is cut out, it can be placed in the bottom of the box to create a flat surface to pour sand on.)
  • 1 quart of sand
  • Felt-tip pen
  • Protractor
  • Funnel
  • Ruler
Instructions for the teacher:
  1. Read The Background Scoop on Sand and initiate a discussion with your class.

  2. Hold the funnel just below the edge of the top of the back of the box and slowly pour all of the sand into the funnel so the sand makes a cone shape along the back panel of the box. (Be careful not to hit the box and ruin your formation.) One student can hold the funnel while the other pours the sand evenly. Try to keep the sand flowing evenly through the funnel. It is better if the funnel is kept ½ full or full while pouring. A third student can record the data while a fourth can measure the angle.

  3. Make a mark carefully on the back panel of the box that is even with the top of the cone. (Point A)

  4. Make a mark carefully on the back panel of the box even with the base of the cone. (Point B) Remove the sand and draw a diagonal line on the back of the box from point A to point B. Measure the distance from the bottom of the box to point A, then make 2 more points one on either side of point A. Connect the points with a straight line. This is the reference line.

  5. Measure the angle of the cone by placing the flat edge of a protractor on the reference line drawn on the back wall lining it up with the center of the protractor at point A as seen in the diagram. Or lay the flat edge of the protractor on the bottom of the box and measure the angle.

  6. Have a quick discussion with your class. Do the students think that a dune made with 4 times as much sand would make a dune with the same angle? Do they have any idea why or why not?

  7. Now make a second dune using four times as much sand. Is the angle the same? How about a sand dune 100 feet tall. Would it fall down?

  8. Copy the following table on the chalkboard or overhead projector and fill it out.
    9. Dune (Pile) # Amount of sand Angle of dune
    1 125 ml  
    2 250 ml  
    3 500 ml  
    4 750 ml  
    5 1000  

     

  9. Ask the students using the funnels and sand: How would you make a sand ridge on a large piece of paper?

  10. Have another short discussion with your students. The sand ridges of Florida were not made with giant funnels. How were they made? Here is a little riddle for the students:

    11. I push without a hand,
    Without a hoe I move the sand,
    Without a voice I still can sigh,
    Unseen, I still can touch your eye.
    Who am I?

Notes
You can carry this activity a bit further by setting up a ridge of fine, dry sand or salt on a large, flat piece of paper positioned at the edge of a table. A student can then carefully blow at table level to cause "blow-outs", and shape ridges in the sand---and even move the whole dune "inland"!

Results
After Part One of this activity, your students should:

  • Understand that flowing sand forms a standard angle of incline regardless of the amount of sand.
  • Understand how sand dunes are formed.
I.A.2-Part 1    Part 2
A. Physical Properties of Sand     I.A.1     I.A.3
B. Animal Tracks in the Sand     I.B.1
C. Glossary     D. Questions for Student Evaluation