Science Assignments

Below is a science homework assignment that is due December 9. Students will type their answer in Google Classroom.

Writing Prompt Question: Why is it important to take care of the earth’s soil?  Answer in a five-sentence paragraph.

What is Soil?

Soils are complex mixtures of minerals, water, air, organic matter, and countless organisms that are the decaying remains of once-living things. It forms at the surface of land – it is the “skin of the earth.” Soil can support plant life and is vital to life on earth.

Soil, as formally defined in the Soil Science Society of America Glossary of Soil Science Terms, is:

1. The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants.

2. The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period.

   
   

So then, what is dirt? Dirt is what gets on our clothes or under our fingernails. It is soil that is out of place in our world – whether tracked inside by shoes or on our clothes. Dirt is also soil that has lost the characteristics that give it the ability to support life.

Soil performs many critical functions in almost any ecosystem (whether a farm, forest, prairie, marsh, or suburban watershed). There are seven general roles that soils play:

1. Soils serve as media for growth of all kinds of plants.

2. Soils modify the atmosphere by emitting and absorbing gases (carbon dioxide, methane, water vapor, and the like) and dust.

3. Soil provides habitat for animals that live in the soil (such as groundhogs and mice) to organisms (such as bacteria and fungi), that account for most of the living things on Earth.

4. Soils absorb, hold, release, alter, and purify most of the water in terrestrial systems.

5. Soils process recycled nutrients, including carbon, so that living things can use them repeatedly.

6. Soils serve as engineering media for construction of foundations, roadbeds, dams and buildings, and preserve or destroy artifacts of human endeavors.

7.  Soils act as living filters to clean water before it moves into an aquifer.

Credit: soils4kids.org.

Below are definitions for students to study for their next science quiz. Quiz date will be announced later.

Soil Characteristics Vocabulary:

 •Humus: Decayed plant or animal matter.

•Topsoil: Top layer of soil.

•Subsoil: Layer of soil underneath topsoil.

•Parent material: Material from which soil is formed.

•Particle size: Includes sand (2.0-.06 mm), silt (.06-.002 mm) or clay (less than .002 mm).

•Porosity: How much space is between particles of soil.  Spaces are filled with air, water or gases.  How do you think porosity affects groundwater?

•Permeability: How fast water flows through soil.  How would permeability be important if you wanted to build a small pond?

Salt vs Fresh Water:

•Composition: Saltwater is made by rocks that have been eroded and become part of a “salty” solution. 

•Density: Saltwater is more dense than fresh water.  For this reason, objects which cannot float in freshwater can float in seawater.

•Electrical Conductivity: Electricity flows more easily through saltwater.  Electricity flows through water by means of small particles called “ions.”  Salt is made up of NA and Cl ions. 

•Viscosity: Viscosity refers to the resistance provided by water.  Saltwater has a higher viscosity due to its salt content.  A swimmer can swim faster in fresh water than saltwater. 

Water Systems:

•Wetland Systems: Areas saturated with water.  Often found along waterways and in floodplains.  Includes swamps, marshes and bogs.

•Ocean Systems: Covers 70% of earth’s surface and contains 97% of earth’s water.  Oceans moderate climate all over the earth.

•River Systems: River’s source and river as it forms a V-shaped valley, a floodplain, meanders and flows into the river’s mouth (e.g. Susquehanna River flows into Chesapeake Bay).

•Watershed: Area drained by a river and its tributaries.

•Tributaries: Smaller bodies of water flow into larger waterways.

•Water quality: Water quality is the chemical, physical and biological content of water. The water quality of rivers and lakes changes with the seasons and geographic areas.