Eighth Grade Science Outcomes

Focus: Physical Science

Motion

1. The velocity of an object is the rate of change of its position.

As a basis for understanding this concept, students know:

a. position is defined relative to a standard reference point.

b. average speed is the total distance traveled divided by the total time elapsed. The speed of an object along the path traveled can vary.

c. how to solve problems involving distance, time, and average speed.

d. to describe the velocity of an object, one must specify both direction and speed.

e. changes in velocity can be changes in speed, direction or both.

f. how to interpret graphs of distance versus time, and speed versus time for motion in a single direction.

g. acceleration results in a change in the motion of an object (i.e., increase or decrease in speed, or change of direction).

h. how to calculate acceleration.

Forces

2. Unbalanced forces cause changes in velocity.

As a basis for understanding this concept, students know:

a. a force has both direction and magnitude.

b. when an object is subject to two or more forces at once, the result is the cumulative effect of all the forces.

c. when the forces on an object are balanced, the motion of the object does not change.

d. how to identify two or more forces acting on a single static object (e.g., gravity, friction).

e. when the forces on an object are unbalanced, the object will change its motion (i.e., it will speed up, slow down, or change direction).

f. Newton’s three laws of motion.

g. the role of gravity in forming and maintaining planets and stars in the solar system.

Structures of Matter

3. Elements have distinct properties and atomic structure. All matter is comprised of one or more of over 100 elements.

As a basis for understanding this concept, students know:

a. the structure of the atom and how it is composed of protons, neutrons, and electrons.

b. compounds are formed by combining two or more different elements. Compounds have properties that are different from the constituent elements.

c. atoms and molecules form solids by building up repeating patterns such as the crystal structure of NaCl (salt) or long chain polymers.

d. the states of matter (solid, liquid, gas, plasma) depend on molecular motion. In solids, the atoms are closely locked in position and can only vibrate; in liquids, the atoms and molecules are more loosely connected and can collide with and move past one another; in gases, the atoms or molecules are free to move independently, colliding frequently. In plasma, gas molecules collide vigorously and form charged particles (ions).

e. how to use the Periodic table to identify elements in simple compounds.

Periodic table of Elements

4. The organization of the Periodic Table is based on the properties of the elements and reflects the structure of atoms.

As a basis for understanding this concept, students know:

a. elements are defined by the number of protons in the nucleus (atomic number). Different isotopes of an element have a different number of neutrons in the nucleus.

b. how to identify sections of the Periodic Table corresponding to metals, nonmetals, and noble gases (inert gases).

c. rationale for the arrangement of the Periodic Table into families (groups) and periods.

d. substances can be classified by their properties, (e.g., melting temperature, density, hardness, heat, and electrical conductivity).

Chemical Reactions

5. Chemical reactions are processes in which atoms are rearranged into different combinations of molecules.

As a basis for understanding this concept, students know:

a. reactant atoms and molecules interact to form products with different chemical properties.

b. conservation of matter.

c. how to interpret chemical formulas and chemical equations.

d. chemical reactions usually release or absorb heat.

e. physical processes (e.g., freezing and boiling), in which a material changes form with no chemical reaction.

f. how to determine whether a solution is acidic, basic or neutral.

Chemistry of Living Systems

6. Principles of chemistry underlie the functioning of biological systems.

As a basis for understanding this concept, students know:

a. carbon, because of its ability to combine in many ways with itself and other elements, has a central role in the chemistry of living organisms.

b. living organisms are made of molecules largely consisting of carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur.

c. living organisms have many different kinds of molecules including small ones such as water and salt, and large ones such as carbohydrates, fatty acids, proteins, and nucleic acids.

Density and Buoyancy

7. All objects experience a buoyant force when immersed in a fluid.

As a basis for understanding this concept, students know:

a. density is mass per unit volume.

b. how to calculate the density of substances (regular and irregular shaped solids, and liquids) from measurements of mass and volume.

c. the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid it has displaced.

d. how to predict whether an object will float or sink.

Earth in the Solar System

8. The structure and composition of the universe can be learned from the study of stars and galaxies, and their evolution.

As a basis for understanding this concept, students know:

a. galaxies are clusters of billions of stars, and have different shapes.

b. the sun is one of many stars in our own Milky Way galaxy.

c. stars differ in size, temperature, and color.

d. how to use astronomical units and light years as measures of distance between the sun, stars, and Earth.

e. stars are the source of light for all bright objects in outer space. The moon and planets shine by reflected sunlight, not by their own light.

f. the appearance, general composition, relative position and size and motion of objects in the solar system, (i.e., sun, planets, planetary satellites, comets, asteroids).

Scientific Method: Investigation and Experimentation

9. Scientific progress is made by asking meaningful questions and conducting careful investigations.

As a basis for understanding this concept, students should develop their own questions and perform investigations. Students will:

a. plan and conduct a scientific investigation to test a hypothesis using the steps of the scientific method.

b. collect and record data using the metric system.

c. evaluate the accuracy and reproducibility of data.

d. distinguish between the variable and controls in a test.

e. interpret graphs constructed from data.

f. construct appropriate graphs from data and develop quantitative statements about the graphed data.

g. apply simple mathematical relationships to determine one quantity given the other two (e.g., speed = distance/time; density = mass/volume; force = pressure x area; volume = area x height).