13. WEATHERING
• Weathering is when rocks are broken down
into smaller pieces by weather.
• Heating and cooling
• Freezing and thawing
• Wetting and drying
• Moving water
• Wind and ice
• Chemical action
17. SOIL IS…
“the portion of the earth's surface consisting of
disintegrated [broken up] rock and humus.
-Dictionary
Editor's Notes
Who can tell us what soil is? Start a discussion about characteristics of soil . We will write what each person says on the board. Connect what they said to the next few slides
We will look if any of these were listed on the board. Students will be asked which of these would they say is in soil and which they think is not a part of soil. Students will be asked to explain their thinking. The discussion will finish with students being told all of these are found in soil.
Students will pass around the gravel, sand, and topsoil bags. They will decide which component of soil has more spaces between each particle? We will talk about how these spaces are filled with air. The order from most spacious to least is gravel, topsoil, sand, and clay. They will record these observations on their index cards. Then students will look at their soil samples to see if there is any spaces for air.
Students will hypothesize which soil absorbs more water. Then students will be split into 3 groups: sand, silt, and clay soil group. They will perform the experiment in their groups. Then we will come together as a whole class and discuss the results. We should see clay and silt retain the water longer and sand dries the fastest. They will record these observations on their index cards.
I will ask is mud found in soil? Yes it’s found in the soil when there is a lot of water. The I’ll ask what types of components in soil create mud? Can sand? No Silt? Yes Clay? Yes Gravel? No Is mud a component that creates soil? No it is soil that is completely moist with water.4. What do you think creates soil? Ill write their predictions on the board
These are the components that make up soil. Let’s say them together. I’ll point to each. We will discuss which predictions on the board were correct and which weren’t and why. Write each of these names on the top of their index cards on the unlined side. All of these components started as rock.
I’ll ask students what is humus? We will talk about students’ predictions. I’ll have them look through their soil samples and pull out any pieces of humus they can find and share with a partner to predict what they think their humus is. If they don’t have any I will give them some. Students will share what they discussed, with their partner, with the whole group. Finally, I’ll tell students that humus is organic material which means it is living or was once living. Add to index card. Students will orally give examples of humus: dead plants, animals, and other previous living things. The more humus there is the darker the soil becomes, because it provides the most nutrients. Nutrient is a substance that provides strength, build up, or promote better health for a living organism (thing). Students will compare their soil samples with a partner to decide who has more humus. I’ll ask them if my topsoil has a lot of humus: yes it’s very dark. Students will find the humus picture in their stack of pictures and glue it to the front of their index card.
I will ask students who had clay in their soil sample? I’ll call on those to explain what properties they noticed about clay: feels sticky, holds a lot of water, very small particles (pieces) that can only be seen under the hand lens. Is there much space for air? No it sticks together. Ask students what things have you done with clay? Mold it or created things from clay. Clay is a great natural resource, something people use that comes from nature, people use to build things. Was anyone’s soil red or had a reddish brown color? It probably had red clay in it which is used to make bricks.
Did anybody have circles on the second column? I’ll call on students who had some properties and what were they? Feels Smooth and silky; holds togetherbut is not clumpy like clay (can’t make a ball); larger particles (pieces) than clay but smaller than sand; absorbs water easily but not as much as clay. Does allow for more air to pass through than clay.
I’ll ask students who has ever played in sand? I will have students tell where they played in sand and properties they noticed about it. Feels rough; falls apart; Holds together when wet but crumbles easily;Particles are not too small and can easily be seen. Draw and label a picture of sand on index card
Ill ask students to come up with adjectives that describe rocks. I’ll emphasize that I am only looking for one word: hard, different colors, different shapes. Not living natural resource (Inorganic).All the components of soil come from broken up rocks. The differences in soil comes from the type of rock the soil came from, the elevation of the land, climate (weather of the area), and also the types of plants and animals in the area. Students will draw and label a picture for rock index card.
Students will get into pairs to come up with an explanation of how rocks break up.
Connect what students said with the types of weathering belowHeating and cooling: rocks expand in heat and get smaller when cold: eventually they will break upFreezing and thawing: example pavement- water gets into small cracks freezes making it expand, which can cause it to crackWetting and drying: rocks can expand when they’re wet and get smaller when they dry : eventually they will break upMoving water: rivers, ocean, and rain can break rocks up after a long timeWind and ice: wind causes pieces of rock to hit each other and break up. Glaciers move pieces of rock and cause wear on bedrockChemical action: water can cause some rocks to dissolve or ground water chemicals can dissolve rocks. Oxygen in the air can cause some rocksto change and break a part.
This is a video clip that shows a bouldering that has gone through weathering and erosion. This is a 2 minute video that talks about frost weathering and shows its effects.
This rock split from water getting into a crack and froze. When the water froze it forced the rock apart.
Thinking about what we just went over about the components of soil. (Think, ink, pair, share) Students will write a definition for soil on their index card. Students will talk about their definitions with a partner and can make changes after discussing this. Once students have shared with a partner pairs will share with the whole class.
We will connect this dictionary definition with the definition students created.
