Activity: From Mud Pies to Bricks
Purpose
To introduce the different components of soils and
the properties which each contributes to the soil
character.
Overview
Students will sift soil to remove organic
materials and pebbles. They will then sift the soil
with smaller meshed sieves to separate clay and sand.
Students will make mud pies by adding water to the
various soil components, letting them dry and
observing the pie's characteristics. Finally,
students will be challenged to create the perfect mud
pie or building brick using combinations of soil
components.
Time
- One class period to sift soils and make mud pies.
- Overnight to dry.
- One class period to experiment with creating
bricks.
- Overnight to dry.
Level
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Key Concepts
- Soil is composed of a variety of materials
- The size of soil particles helps determine the
soil characteristics
- Soil is important as a building material
Skills
- manual dexterity
- observation
- calculating (measuring or weighing soil)
- experimental design
- testing results
Materials and Tools
- soil
- several sizes of mesh screen or sieves for
sifting
- straw (dried grass clippings)
- additional powdered clay and sand
- old ice cube trays (for brick molds)
- small plastic lids or plates (for pies)
- plastic table cloth
Keywords
- Activity; Soil; K-3; Soil Texture; Soil Moisture
|
Background
Soil is made up of many things such as organic material,
pebbles, and different size grains of broken-down rock (sand,
silt and clay). How much water a soil will hold, how easily water
passes through the soil, and what happens to the soil as it dries
depends on the combination of these materials in your particular
soil. Soil with too much clay may crack as it dries - you have
probably seen pictures of ground with huge cracks or observed the
cracking at the top of a mud puddle when larger, heavier
particles have settled to the bottom. Soil with too much sand may
not hold together well or be strong enough as a building
material.
Soil has been used as a building material for thousands of
years, and is still one of our most important building materials.
In dry regions houses built of adobe bricks last hundreds of
years. Concrete and bricks are common everywhere. Whether you are
making concrete or adobe blocks, it is important to understand
the importance of having the right elements in your soil mix.
What to Do and How to Do It
Making Observations and Asking Questions
- Ask students to examine the soil carefully using their
eyes, hands, and a magnifying glass.
- Make a list of the things students observe about the
soil. For example: different size, shape, and color
of grains, other soil materials such as sticks or leaves,
'dustiness', weight, etc.
- Ask students if they think the soil would be different if
all of the particles were alike or if some parts were
missing. How would it be different?
Discovering Different Sizes
- Starting with the largest mesh sieves, sift the
soil.
- Place what does not go through the sieve in one
pile - these are the largest particles.
- Ask students to examine the 2 piles. How are they
alike and different? Can they think of reasons
why each pile would be good for different things.
- Take the soil that passed through the sieve and
sift it through the next smaller mesh.
- Keep what did not go through the sieve separate,
and continue sifting through smaller mesh
screens. Students will now have several piles of
soil separated by the size of the particles.
- Ask students to identify words that describe the
different piles of soil they now have. Identify
the concept of particle size: sand, silt and
clay. Words might include: powdery, rough,
smooth, dusty, etc.
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Discovering Texture and Soils as Building Materials
- Discuss with students the importance of soil as a
building material. Ask students to identify things that
are built with soil. Example: concrete sidewalks,
brick buildings
- Have students describe how they would make a brick using
the soil they have.
- Ask students to describe the characteristics of a good
mud pie or brick. For example: hardness, cracking,
resistance to breaking or water, etc.
- Ask students to guess which pile of soil would make the
best mud pie or brick. Why did they choose the pile of
soil that they did? What will happen to each pile when
water is added to it?
- Have students make mudpies or bricks from the soil in
each pile by adding water then molding by hand or putting
into a mold like an old icecube tray.
- Dry completely in the sun or in a warm place.
- Ask students to test the mud pies or bricks that they
made for breaking, cracking, smoothness, etc.. List what
is good or bad about each one.
- Challenge students to create the perfect mudpie or brick
by combining different amounts of the soil elements they
sifted out. Additional sand, clay or organic material may
be provided, especially if your original soil did not
contain very much of one of these elements. Have students
measure or weigh the different ingredients and write a
'recipe' so that they can compare with other students or
recreate their creation.
- Older students can figure the percent weight of each soil
component in their recipe.
| Recipe Card |
| Ingredients: |
amount: |
| clay (small particles) |
|
| silt (medium particles) |
|
| sand (large particles) |
|
| other |
|
| other |
|
Further Investigations
- What happens when the dried bricks get wet? Have students
use a spray bottle to investigate how well their bricks
resist water. Research how adobe houses are protected
from rain.
- Examine a piece of broken brick. What soil elements can
you identify? Why are bricks water resistant?
Assessment
On a field trip ask students to identify places where the soil
seems to have more sand or clay. How did they identify these
places? What effect might the soil texture have on the soil use?
Last updated: 5/3/97
Comments? globe@hwr.arizona.edu