PEBBLES, SAND, AND SILT

BACKGROUND• Observing rocks and beginning to sort

them into groups are the initial steps for students to take in the role of geologists.

• Observing is a fundamental process in geology.

Summative Assessment

Investigation 1: First Rocks1. Three Rocks2. Washing Three Rocks3. First Sorting4. Sorting Games5. Start a Rock Collection

Part 1: Three Rocks• Focus questions

How are rocks different? What happens when rocks rub together?

Part 1: Three Rocks• Vocabulary

– Rock– Dust– Geologist

• Respond to focus question

Part 2: Washing Three Rocks• Focus question

What happens when rocks are washed?

Part 2: Washing Three Rocks

Part 2: Washing Three Rocks• Find a Rock

ROCK NAMES• Basalt is the gray, smooth

rock. It was once the hot liquid lava that came out of a volcano.

• Tuff is the light, soft rock. It has ash in it from the fires of the volcano.

• Scoria is the reddish bubbly rock. It was once the bubbly top of the lava.

Part 2: Washing Three Rocks

• Vocabulary– Basalt– Tuff– Scoria

• Respond to focus question

Part 3: First Sorting• Focus question

How are some rocks the same?

Part 3: First Sorting• Vocabulary

– Rough– Smooth– Pointed – Large– Small– Crystal– Dull

Part 4: Sorting Games

Concept Development• Vocabulary

– Any new descriptive words• Respond to focus question

Part 5: Start a Rock Collection• Focus question

What rocks can we find around us?

Part 5: Start a Rock Collection• If you wanted to find some rocks to

collect, where would you look?

Where to Look for Rocks

FOSS Science StoriesExploring Rocks

EXTENSIONS• Language Arts

– Geologist Tool Kits

• Math Problem A• Math Problem B• Art

– Make rock people or pets

• Games– Rock checkers

Investigation 2: River Rocks 1. Screening River Rocks2. River Rocks by Size3. Sand and Silt4. Exploring Clay

Investigation 2: River Rocks• Background

– The solid, liquid, and gaseous materials that make up Earth and its atmosphere are know collectively as earth materials.

– Rock that has broken away from the continuos layer of bedrock is found in particles that range from minuscule to the gigantic.

– Geologists classify rock particles by size.

Size Ranges Used by FOSS• Clay - <0.004 mm

• Silt - 0.004 - 0.062 mm

• Sand - 0.062 - 2 mm

• Gravel - 2 - 4 mm

• Pebble - 4 - 64 mm

• Cobble - 64 - 256 mm

• Boulder - >256 mm

Part 1: River Rocks • Focus question

How can rocks by sorted by size?

DISCUSS RESULTS

Concept Development• Vocabulary

– Earth material– Screen– Separate– Size– Sand– Gravel– Pebble

• Respond to focus question

Part 2: River Rocks by Size• Focus question

How else can rocks be sorted by size?

Part 2: River Rocks by Size

Concept Development• Vocabulary

– Cobbles– Boulder

• Respond to focus question

Part 3: Sand and Silt• Look at the vials with sand• Look at it carefully and describe how it looks,

feels, and sounds• Place the sand on a paper plate to do your

observations– Use a spoon to move sand around

• Plate shaking (5 minutes)– Shake the plate gently back and forth on the table.– Place a pinch of sand in the vial and use the hand

lenses to make observations.

DISCUSS OBSERVATIONS• Describe what you noticed about the

sand.– Are the sand particles all the same size?– What do the sand particles look like?

DISCUSS OBSERVATIONS• What do you think might happen if you

mix sand and water?• Use the paper plate as a funnel to put the

sand back in the vial.• Fill the vial with water.• Watch what happens to the water and

sand.

QUESTIONS• What happened to the water that was poured

on the sand?• What happened to the sand?

– Place the cap on the vial and shake it.– What happened to the water and sand after you

shook the vial?• Is the water clear now?

– Why not?• Let them settle overnight.

DRAWING SHEETS• Draw what you see on the vials (p. 8).

– Vials were set up earlier.– What do you see in the vials?– How many layers do you see?– Where is the sand?– What do you see on top of the sand?

• The layer of material on top of the sand is called silt. Silt is a particle of rock much smaller than sand. It’s the rock size that mud is made of.

SILT• Label the layers in your drawings. • The layers should be called: sand, silt,

and water.• What should the space between the top of the

water and the vial cap be labeled? • Feel the silt.

– Pour off the water in the vials into a 1/4 container.– Carefully, touch the top layer of silt. Try to pull some

out and rub it between your fingers.

CLEAN UP

Take vials to clean up area.Add a little water, shake and

dump the sand/water in basin.

Part 4: Exploring Clay• Get a cube.• Look at this new earth material.

– What is this material called?– What is special about this material?– What can you do with it?– What is happening to your hands as you work with

this material?– What is the smallest size of rock we’ve worked so far?

• Clay is made of pieces of rock even smaller than silt. • The dust in your hands is actually dry clay particles.

Part 4: Exploring Clay• Pinch off a small piece of clay, about 1 cm.• Predict what do you think will happen if you put

the small ball of clay in a vial with water.– Put the small ball of clay in the vial.– Pout water into the vial almost to the top.– Watch what happens to the clay in water for a minute or two.– Cap the vial and shake it to see what happens.

• What is happening to the clay?• Is the water changing?

– Let it sit overnight

Part 4: Exploring Clay• If dry, observe and squash the clay balls for a few

minutes.• How can you get the clay soft and pliable again?

– Put ball in a plastic cup and add a little water.• Set aside, let it sit for a while.

• Observe pre set vials.– Compare to shook vials.– Draw the clay vial and label layers.

QUESTIONS• What was the same in both vials?• What was different in both vials?• Look at the vial with the ball of clay.

– What do you see?• Save the clay.• Clean up.• Extensions.

Investigation 3: Using Rocks1. Rocks in Use2. Looking at Sandpaper3. Sand Sculptures4. Clay Beads5. Making Bricks

Part 1: Rocks in UseField trip.

Part 2: Looking at Sandpaper• Review sand• Important sand use: sandpaper• Pick up sandpaper

– Use the hand lenses to observe the sandpaper.

– Rub fingers gently over the paper.

Part 2: Looking at Sandpaper• Vocabulary.

– Three textures.• coarse - largest pieces• medium - middle-sized pieces• fine - smallest sand

Part 2: Looking at Sandpaper• Place white paper over the sandpaper• Rub with the side of a pencil or crayon to

record the sandpaper texture• Label the rubbings• Identify sandpaper with the eyes closed• Rub sandpaper together

– Share observations• Clean up

Part 3: Sand Sculptures• Review the properties of sand.• Sand matrix (make it the night before)

– Matrix is a material that holds articles of material together

• Use two vials of sand and add one spoonful of matrix on top of the sand on a paper plate

• Mold sand mixture• Allow sculptures to dry

Part 4: Clay Beads• Review properties of clay

– Stick together when is molded.– It hardens when it dries.– We will use these properties to make

beads, then string the beads into necklaces.

Part 4: Clay Beads• Techniques

– Get a 3 cm ball of clay– Smooth with water if it cracks.– Use a pencil or straw to carve shapes and lines

on the clay. – Poke with a piece of straw and let dry.– Should dry in 1-2 days.– Paint your creations when clay is dry.– Use a piece of yarn to make necklaces.

Part 5: Making BricksExtensions

Inv 4: Soil Explorations1. Homemade Soil2. Soil Search3. Studying Local Soil

Part 1: Homemade Soil• Look at new material

– Describe the appearance, feel, and smell of the material

– Humus (HUW mus)• It’s mostly plant material that has decayed or

rotted

Part 1: Homemade Soil• Making new earth material

– Recipe: 2 cups of sand, 1 cup of gravel, 1 cup small pebbles

– Add humus to the mixing• The name for the mixture we just made is

soil. Soil is a combination of earth materials. Soil covers almost all of the Earth’s land surface

SEPARATING SOIL• Place a sample of soil in a paper plate.

– Observe. – Try to separate by hand.– By shaking.

• Discuss observations.• Use screens to separate soil.

– Where you able to separate the soil with the screens?– Where did the humus end up?

• How can you separate the humus?

START SOIL AND WATER INVESTIGATION

Set up your own investigation.Pick up materials from station.

DISCUSS RESULTS

Clean up

Part 2: Soil Search

Field Trip

Part 3: Studying Local Soil

Design an investigation.Compare to the homemade soil.

EXTENSIONS