Science Standards

†	•	Physical Science
†	•	Unifying Concepts and Processes

A fluid is something that flows. Highly compressible fluids are usually considered gases; essentially incompressible fluids are usually considered liquids. Fluids tend to conform to the shape of a container. On Earth's surface, liquids tend to fill the bottom of an open or closed container and gases tend to fill closed containers.

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Science Standards

†	•	Physical Science
†	•	Unifying Concepts and Processes

Rheology is the scientific study of the deformation and flow of matter.

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Science Standards

†	•	Physical Science
†	•	Science and Technology
†	•	Unifying Concepts and Processes

The critical point is the temperature at which the differences between liquids and gases disappear. Above that temperature, the liquid smoothly transforms to the gaseous state; boiling disappears.

Mathematics Standards

†	•	Mathematical Connections
†	•	Mathematics as Communication
†	•	Mathematics as Problem Solving

Science Standards

†	•	Physical Science
†	•	Science and Technology
†	•	Unifying Concepts and Processes

Hydrostatic pressure is the result of the weight of a material above the point of measurement.

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Mathematics Standards

†	•	Mathematical Connections
†	•	Mathematics as Communication
†	•	Mathematics as Problem Solving
†	•	Measurement

Science Standards

†	•	History and Nature of Science
†	•	Physical Science
†	•	Science and Technology
†	•	Science as Inquiry
†	•	Unifying Concepts and Processes

There are three temperature scales commonly used in the world. The Kelvin scale, the Celsius temperature scale, and the Fahrenheit scale. The SI unit for temperature is the Kelvin. In most scientific laboratories, temperatures are measured and recorded in Kelvin's or degrees Celsius. The Celsius scale is used for weather reporting in most of the world. The United States and some other countries use the Fahrenheit scale for weather reporting.

The Kelvin scale is defined around the triple point of water (solid ice, liquid water, and water vapor coexist in thermal equilibrium) which is assigned the temperature 273.16 K. This is equal to 0.01C and 32.02F. Absolute zero, the coldest anything can get, is 0 K, -273.15C, and -459.67F.

Questions for Discussion
· How do you convert between these different temperature scales?
· What are the boiling and freezing points of water on all these scales, at 1 atm pressure?

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Science Standards

†	•	Physical Science
†	•	Science and Technology
†	•	Unifying Concepts and Processes

A semiconductor is a substance, such as germanium and silicon, that is a poor electrical conductor at room temperature but is improved by minute additions of certain substances (dopants) or by the application of heat, light, or voltage; a material with a forbidden energy gap less than 3 eV.

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Schematic of silicon tetrahedra. The top view is of a crystalline ordered structure. The bottom view is of a disordered glassy solid.           Questions for Discussion · What is an ordinary drinking glass made from? · What different things are added to glass to change its properties? · What natural processes produce glasses? · What are the differences between how glasses and crystalline solids fracture?

Science Standards

†	•	Physical Science
†	•	Science and Technology
†	•	Unifying Concepts and Processes

An alloy is a combination of two or more metals.

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Mathematics Standards

†		Geometry
	•	Geometry from an Algebraic Perspective
	•	Geometry from a Synthetic Perspective
†	•	Mathematical Connections
†	•	Mathematics as Communication

Science Standards

†	•	Physical Science
†	•	Unifying Concepts and Processes

One of the important characteristics of a solid is its shape. On a visible scale, the function of some solids may depend on the ability to sit in a stable manner on a surface or to fit tightly into some configuration. On a smaller scale, the structures of crystalline solids are defined by the ordered placement of atoms. The basis of understanding crystalline structure and the shapes of solids is a knowledge of the definitions of two-dimensional shapes (polygons) and three-dimensional solids (polyhedra). A simple k-sided polygon is defined by connecting k points in a plane with line segments such that no edges intersect except at the defining points (vertices). The sum of the angles in any polygon equals 2x(k-2)x90. Specific names given to some
simple polygons are given below.

Name	# of Sides (k)
triangle	3
quadrilateral	4
pentagon	5
hexagon	6
heptagon	7
octagon	8
nonagon	9
decagon	10
undecagon	11
dodecagon	12

Regular polygons are those for which all the sides are the same length and all the angles are the same. The angles of a regular polygon are defined by q=(k-2)x 180/k.

Questions for Discussion
· Discuss special cases of triangles and quadrilaterals such as isosceles triangles, parallelograms, trapezoids.
· What is the common name for a regular triangle? For a regular quadrilateral?
· Is there a general equation for the area of any polygon'?

Regular polyhedra (or the Platonic Solids) are listed and shown below.

Name	Formed By
tetrahedron	4 triangles
cube	6 squares
octahedron	8 triangles
dodecahedron	12 pentagons
icosahedron	20 triangles

The Five Regular Polyhedra or Platonic Solids Top-Tetrahedron; second row left-Cube: second row right- Octahedron; third row left-Dodecahedron; third row right-Icosahedron. Questions for Discussion · What do you think of as a cylinder and cone? · What are the general definitions cylinder and cone'? · What shapes are some mineral samples you have in your classroom? · Investigate the crystalline structure of halite (rock salt), fluorine, quartz, diamond, iron.

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Science Standards

†	•	Earth and Space Science
†	•	Physical Science

Regolith is a layer of powder-like dust and loose rock that rests on bedrock. In the case of the moon, fragmentation of surface rocks by meteorite bombardment created much of the regolith material.

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