Skip to main content Scroll Top
The FOLLOWING activity draws from the content in the page WEATHERING AND EROSION.   
Fig. 1. A sideways glance along the surface of the beach reveals an array of colors amongst the grains. (Image courtesy of <a href='https://www.maxpixel.net/Sea-Vacation-Beach-Ocean-Hawaii-Tropical-Sparkle-2546961'>Max Pixel</a>)
Fig. 1. A sideways glance along the surface of the beach reveals an array of colors amongst the grains. (Image courtesy of Max Pixel)

Phenomenon:

In a handful of sand, there can be many colors (Fig. 1).

Inquiry:

Why are there different colors of sand grains in Hawai’i?

 

Guiding Questions:

  1. How do different types of sand form?
  2. Why is sand color different from beach to beach?

Activity:

In this activity, you will make observations about the effects of weathering. You will conduct an experiment to investigate whether sand collected from around Hawaiʻi is volcanic or biological in origin.

Materials:

  • Sand samples from different beaches—at least 3 samples (Hint: preferably black sand, white sand, and one with mixed colors)
  • Small bowl or dish
  • Magnifying glass
  • White school glue (or any glue that dries clear). Clear tape can also be used.
  • White distilled vinegar
  • Teaspoon (or small spoon)
  • Sand inquiry Student Worksheet and Teacher Guide (attachment below).
Student Worksheet: Sand Inquiry
  • This teacher guide follows the procedure written here and in the student worksheet with additional instructions and guidelines. We highly recommend starting this activity by introducing the Phenomenon, Inquiry, and Guiding Questions from the top of this webpage
Teacher Guide: Sand Inquiry
  • Optional: Extra pages to explore additional sand samples
Additional Sand Inquiry Pages

   

Vinegar Test:

  • Vinegar is a weak acid that reacts with and dissolves calcium carbonate.
  • The shells and skeletons of many marine invertebrates (like corals, urchins, clams, plankton, etc.) are made of calcium carbonate. Calcified algae also contain calcium carbonate.
  • Vinegar releases bubbles of carbon dioxide when it dissolves calcium carbonate. If there is no calcium carbonate present when you add vinegar, there will not be any bubbles.

Procedure:

  1. Follow your worksheet to explore and observe your sand samples using a toothpick and magnifying glass.
  2. Glue sand from each location onto your worksheet, and answer the preliminary questions.
  3. What would happen if you add vinegar (a weak acid) to
    1. biological sand (one with pieces of shells, coral or algae)?
    2. volcanic sand (sand from volcanic rock)?
  4. Test your samples to determine the source of sand. Record your findings in the worksheet table.

Sample #1: White Sand

  1. ​Place a teaspoon of white sand into a bowl or dish.
  2. Slowly add a teaspoon of vinegar.
  3. Observe and record the reaction.

Sample #2: Black Sand

  1. Place a teaspoon of white sand into a bowl or dish.
  2. Slowly Add a teaspoon of vinegar.
  3. Observe and record the reaction.

Sample #3: Mystery Sand

  1. Place a teaspoon of white sand into a bowl or dish.
  2. Slowly add a teaspoon of vinegar.
  3. Observe and record the reaction.

Additional Samples

  1. Explore more sand samples using the additional sand inquiry pages!

 

Activity Questions:

  1. What differences did you observe between the different colors of sand?
  2. What do the differences you observed tell you about the source of that sand?
  3. If one sand sample bubbled a little bit but the other sample bubbled a lot when you added vinegar, what would this tell you about the amount of biological material in each sample?
  4. How do you think the sand got to the beach?
  5. Did you see anything else in the sand? Describe any items that do look biological or volcanic.
  6. How do you think non-sand items got to the beach?
  7. Do all beaches get their sand in the same way? Explain your ideas.

Further Investigations:

  1. Map out the different sand beaches around Hawaiʻi. Glue/tape sand samples to a large map.