Why is there sand at the beach?
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DISCUSS (1 of 2):

Why do you think the sand is purple?

DISCUSS (2 of 2):

Imagine you were at Pfeiffer Beach. How could you look for clues to help you solve the mystery of where the purple sand comes from?

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DISCUSS:

Can you think of a way tiny pieces of these rocks could move from the mountains all the way to the beach?

Hint...

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DISCUSS: What do you think would happen if the rocks in the river crashed into each other? Could this explain how there’s sand at the beach?

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Extensions

Below are ideas for extending this topic beyond the activity & exploration which you just completed.

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Readings:

These readings about sand are free with registration on ReadWorks, a nonprofit that provides Common-Core-aligned readings. All readings include comprehension questions.

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Writing Prompt

Ask students to pretend to be a big rock high in the mountains. Tell them their story starts when a thunderstorm washes them into a river. Ask them to imagine what might happen next. Have them think about where their journey could end.

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Activity: Take a Closer Look

  • Bring in some beach sand.
  • Have each student sprinkle some sand on a piece of white paper and some sand on a piece of dark paper.
  • Take a close look. Use a magnifying lens if you have one.
  • Ask students how many different colors of sand grains they can they can find. What else do they notice about the sand?
  • For an even closer look at sand grains, visit Dr. Gary Greenberg’s gallery of sand grains. These photographs show sand viewed through a microscope.
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Image & Video Credits

Mystery Science respects the intellectual property rights of the owners of visual assets. We make every effort to use images and videos under appropriate licenses from the owner or by reaching out to the owner to get explicit permission. If you are the owner of a visual and believe we are using it without permission, please contact us—we will reply promptly and make things right.

Exploration
kids at the beach by Image used under license from Shutterstock.com: bikeriderlondon
white sand beach by Image used under license from Shutterstock.com: Rob Marmion
girl on the beach by Image used under license from Shutterstock.com: ori-artiste
sand castle by Image used under license from Shutterstock.com: Kris Wiktor
Southwick Beach State Park by Easchiff
hand in sand by Image used under license from Shutterstock.com: kasidit
kid at Pfieffer Beach by The Offshore Aquaholic
purple sand by The Offshore Aquaholic
purple sand beach by Carson
kid holding sand by Image used under license from Shutterstock.com: Albina Glisic
footprints on purple beach by Image used under license from Shutterstock.com: mhgstan
hand holding purple sand by Akos Kokai
magnifiying glass by Image used under license from Shutterstock.com: underworld
close up of sand by Image used under license from Shutterstock.com: Mr Twister
zoomed view of sand by Image used under license from Shutterstock.com: AlexussK
green sand beach by Image used under license from Shutterstock.com: Alexander Demyanenko
close up of green sand by Brian W. Schaller
cliffs facing the beach by Image used under license from Shutterstock.com: Noradoa
close up of cliff by Image used under license from Shutterstock.com: jennyt
scuba diver by Image used under license from Shutterstock.com: Rostislav Ageev
Lepidolite (purple rock) by Spirit Rock Shop
purple mountains by Gonzo fan2007
falling rocks sign by Image used under license from Shutterstock.com: Michael Leslie
rock crashing down mountain by Joraj Dason
beach flooding by Muhammad Moolla
fast flowing river by Hayk Arakelyan
rocks flowing down river by Internet Geography
big blue waves by Image used under license from Shutterstock.com: bus109
chair and beach umbrella by Image used under license from Shutterstock.com: Aleks Melnik
clouds by Image used under license from Shutterstock.com: nikiteev_konstantin
mountains sillhouette by Image used under license from Shutterstock.com: Alex Ghidan
ocean concept by Image used under license from Shutterstock.com: Nikita Konashenkov
sand texture by Image used under license from Shutterstock.com: Ursa Major
Rainbow Beach by Cassarazzi
green rock by Image used under license from Shutterstock.com: Helen Cingisiz
hornocal by Lahi
close up of rainbow beach by cordyceps
stream on the beach by Humphrey Bolton
Activity
rushing river in Smoky Mountains by GreatSmokyMountains (© GSMA 2010. All rights reserved.)
turtles by Image used under license from Shutterstock.com: Dmitri Ma
rushing river by fccysf
Print Prep
Activity Prep

In this Mystery, students investigate the effects of rocks tumbling in a river. Based on their observations, they construct an explanation for why there is sand at a beach. In the activity, Rocking the River, students pretend to be a river and tear up pieces of construction paper to model what happens to rocks as they travel along the river.

Preview activity

Number of students:
Colored Construction Paper
3 sheets per group
Draw the River Rocks printout 1 per student
River (5 sheets) printout 1 per group
Prep Instructions

We recommend students work in groups of four. Homeschool students can work alone.

Prepare “Paper Boulders”

Cut or tear each sheet of construction paper into about 12 pieces. We used a paper cutter to cut many sheets at the same time, making irregularly shaped pieces, but tearing or cutting with scissors will also work.

randomly cut paper

Each group (or single homeschool student) should start with 3 sheets worth of boulders (about 36). We recommend providing plenty of boulders at the beginning so that the students will still have large boulders at the end of the activity. That way, students will be able to see how the sizes of the rocks change as they move downstream.

Extensions
Download this Mystery to your device so you can play it offline: