Activity at a Glance
The Scoop on Moon Dirt

Purpose
Introduce children to different characteristics of soil and how it is formed on Earth and the Moon. Children will learn that the Lunar Reconnaissance Orbiter Mission will provide information to scientists about characteristics of materials found on the Moon’s surface.

Overview
Children examine two different local soil samples and compare them to lunar “soil” simulant. Children explore how soil forms on Earth by using water to wear down a “rock” of sand and ice. Next, they replicate the effect of wind using sandpaper and dry, brittle bread. Processes of soil formation on Earth are compared to those on the Moon, where children will use rocks and graham crackers to model impactors pulverizing the lunar surface, creating lunar “soil” (regolith). This activity is a modified version of the activity "Regolith Formation" from "Exploring the Moon - A Teacher's Guide with Activities for Earth and Space Sciences."

Concepts

• Different soils have different properties (color, texture, composition)
• Lunar “soil” - regolith - does not have any organic components, like Earth soil
• Different soils form from different rock types and under different conditions
• Earth’s rocks break down (weather) through the action of water and wind (other physical, chemical, or biological weathering mechanisms, for example root formation, freezing and thawing, or leaching, are not addressed)
• Lunar “soil” - regolith - forms when impactors strike the Moon’s surface and pulverize the rock

Age Level
Part A. Examining Soils is primarily intended for children ages 6–11
Part B. Making Regolith is primarily intended for children ages 8–11
Note that Part A appropriately can be followed by the impact activity of Part B rather than all of Part B

Time
Part A. Examining Soils – 30 minutes
Part B. Making Regolith – 45 minutes

Materials
For the group:

• Poster paper
• Markers
• Transparencies of lunar footprints, lunar surface, Moon, Moon showing different mineral types
• Overhead projector

For each team of 3–4 children
Part A. Examining Soils

• On separate paper plates

• Local soil sample 1 (label plate as Sample A
• Local soil sample 2 (label plate as Sample B)
• Lunar soil simulant (label plate as Sample C)

• Magnifying glass (5–10x)
• Magnet
• Several toothpicks
• Paper, writing instruments

Part B. Making Regolith

• One margarine container filled with water and sand, that is frozen
• Access to a sink with flowing water (can be done with pitchers of water, although the effect is not as dramatic)
• Dish tub
• Two pieces of dry, brittle bread
• ~2 x 2 inch piece of coarse sandpaper
• One large plastic tub or cardboard box with high sides
• 10–15 graham crackers (enough to cover the bottom of the tub with two layers)
• Fist-sized rock or a pound box of baking soda, wrapped in aluminum foil

Correlations to National Standards

Physical Science – Content Standard B (Grades K–4)

Properties of Materials

• Objects, and materials, have many observable properties
• Objects can be described by the properties of the materials from which they are made and those properties can be used to separate or sort a group of objects or materials.

Grades 5–8

• Substances have characteristic properties

Earth and Space Science – Content Standard D (Grades K–4)

Properties of Earth Materials

• Earth materials are solid rocks and soils, water, and gases of the atmosphere. The varied materials have different physical and chemical properties.
• Soils have properties of color and texture

Grades 5–8

• Soil consists of weathered rocks and decomposed organic material from dead plants, animals, and bacteria. Soils are often found in layers, witheach having a different chemical composition and texture

Science and Technology – Content Standard E (Grades K–4)

Understanding About Science and Technology

• People have always had questions about their world. Science is one way of answering questions and explaining the natural world.

Activity
The Scoop on Moon Dirt

Before You Begin

• Fill the margarine tubs ~3/4 full with sand; add water to cover the sand and freeze lightly.
• Collect two very different soil samples from your local area, perhaps from a field, a flower bed, or the area near a stream.
• Label and prepare the sample plates for each group.

Part A. Examining Soils
Invite the children to tell you what they know about dirt or soil.

• What is it made of? Where is it found?  Are there different types of soils?

Introduce them to the Lunar Reconnaissance Orbiter Mission — LRO — to be launched in 2008! The LRO Mission will orbit the Moon for one year. Some of the instruments on board will provide information about properties of lunar soil, such as its color, minerals it may contain, thickness, how compact it is, and if it contains frozen water. The LRO instruments will also help scientists to map the lunar surface, collect information about how temperatures on the Moon change, and find if frozen water exists in deep, dark craters or at the cold polar regions.

Ask the children to share what they know about the Moon. Remind them that the Moon has no water and no atmosphere, in addition to other insights they may share.

Divide the children into groups. Explain that they will be investigating several different dirt or soil samples, and their job is to describe the characteristics. 

• How might they describe soil?  Note their responses — color, size of materials in the soil, types of materials in the soil. 
• What might a magnifying glass help them determine? (More details about what is in the soil)
• What about a magnet? (If any of the materials are magnetic)

Let the groups explore the different soil samples. Have them describe what they are finding. 

Remind them that they should not taste the samples and that they can use the toothpicks to probe the soil! Scientists examining lunar samples do not handle them; lunar materials are kept under very sterile conditions in the laboratory so that they are not affected by water or particles in Earth’s atmosphere. Lunar samples are kept in sealed work boxes that have holes where gloves are attached. Scientists work with the samples using the gloves. 

Bring the children back to the main group and ask them to share what they observed about each of the three samples; write their responses on poster paper.

• What were the colors of the different soils?
• Did some break apart more easily than others?
• What did they see when they looked under the magnifying glass? Were the sizes of the particles the same or different? How big were they?
• What happened when the magnet was passed over each sample?
• What materials made up each of the different soils? 
• Did any of the samples have organic material — material from living things like trees or grass? 
  (Share that the term “regolith” can be used for all of the samples; regolith means the loose rock material on the surface. Commonly, ”soil” is used for samples that contain mineral and organic — plant — material.)  Which of the samples are soils? Which are regolith?
• Were any of the soils dry? Wet? Have a smell? Like what?
• What clues do the soils give about how or where they formed? (Roots tell us that plants were present where the soil formed; living roots also help to break soil down!)
• Where do the children think the different samples came from? Share that one sample is regolith, like what we find on the Moon — it is not an actual sample of lunar regolith, but very much like one. Can they guess which one? What did they base their hypothesis on?
• Share the image of the astronaut’s boot print or the Moon buggy on the moon (URL). Is there any evidence of lunar “soil”/regolith? What does it look like?

After they determine which sample is which, let them know where you collected the samples and which is the lunar regolith simulant. They may wish to re-examine the samples.

• Why might these samples be soooooo different? (They formed from different materials)
• Where does soil — or regolith — come from? (The breakdown of rock; the children may need help thinking about this)

Have the children think about the different soils around the library or their home. There are garden beds and top soil where grass grows. There may be other types of soil — either naturally in place, or put there by humans. Each soil has its own characteristics and depends on what kind of rock it formed from and the conditions under which it formed (wet or dry, cold or hot).  

Regolith found on the Moon also formed from different rock types. Some have more of one kind of element than others — like aluminum or titanium, if they formed from rocks with these types of elements. Others may contain frozen water in the spaces between mineral and rock particles. Using an instrument called the Lunar Exploration Neutron Detector (LEND), the LRO mission will help us identify — and map — different properties of lunar regolith.

Part B. Making Regolith
Modified from Exploring the Moon, A Teacher’s Guide with Activities

Invite the children to think about different ways regolith can form. 

• What helps to breakdown rock on Earth? (Flowing water, the expansion of freezing water, wind and wind carrying particles, plant roots widening cracks in rocks. The children may think of some of these ideas; the next part of the activity will give them first hand experience with flowing water and wind).
• How might formation of regolith on the Moon be different from Earth?

Place the children back into their groups.  Provide each group with the frozen block of water and sand and ask them to imagine that this is a rock — a sandstone! Have the groups place their “rock” in the dishpan under the faucet and turn the water on at a slow to medium stream.

Bring the children back together to discuss what they found.

• What happens to the rock? (The water wears it away).
• What does this tell us about how water contributes to the breakdown of rocks? 
• Does this happen on Earth? (You bet!)
• Is there any flowing water on the Moon’s surface? (Nope)
• Does water help form regolith on the Moon? (Nope).

Now invite the children to explore how wind can break down rocks. Provide each group with a piece of dry, brittle bread and ask them to imagine it is a rock. 

• What happens when their hand — acting like the wind — brushes across the bread? (Small crumbs may fall from it)
• What happens when they rub a piece of sand paper across the surface? (Many more crumbs break away from the surface!). 

Bring the children back together to discuss what they observed.

• What process does this represent? (Sometimes the wind is strong enough to carry particles of rock. These particles act like the sand paper when they are blown against rock surfaces)
• What does this tell us about how wind contributes to the breakdown of rocks? 
• Does this happen on Earth? (You bet!)
• Is there any wind blowing on the Moon’s surface? (Nope; the Moon has no atmosphere, so there is no wind)
• Does wind help form regolith on the Moon? (Nope).

So what does make regolith — the lunar “soil?” Do the children have any ideas?  Show them the image of the Moon (URL). What are the round shapes on the Moon’s surface? How do they form?

Divide the children back into groups and provide each group with the container of graham crackers and large rock. The graham crackers are the lunar surface, the rock is a large asteroid! Ask the children to drop the asteroid, from about waist high, into the container.

• What happens?
• Have them repeat the process 5 times. What do they observe?
• Have them repeat the process ~20 more times. What do they observe?

Bring the children back together to discuss their observations and thoughts.

• What process does this represent? (Impactors striking the surface of the Moon — or Earth! — breaking down the surface rocks into regolith)
• What changed from 1 impact to 5 to 20? (The graham cracker rocks became more broken and the crumb regolith became thicker and finer)
• What does this tell us about how impacts by asteroids and comets contribute to the breakdown of rocks? 
• Does this happen on Earth? (Yes, but only rarely. Earth’s surface is constantly “recycled” by wind and water and other processes, so the evidence of many of these craters has been erased. Earth’s atmosphere also helps to protect us from being struck by smaller asteroids — they burn up in our atmosphere — making the beautiful streaks of light — meteors — that we occasionally see.)
• Do impacts occur on the Moon? (Yes, also rarely now, but wind and water do not flow on the Moon’s surface, so once craters form, they are not altered by other processes, unless they get hit by another rock from space! The Moon’s surface preserves a record of almost 4 and a half billion years of impact after impact after impact after impact!)
• Do impacts  help form regolith on the Moon? (You bet! They are the main process forming lunar regolith.)

Revisit with the children what they have learned.

• How do soils form on Earth? 
• Do these same processes form regolith  on the Moon?
• How does regolith form on the Moon? 
• What will the LRO tell us about lunar “soils?”

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Last updated
May 9, 2006