8th Grade Science Overview

The empty spaces in a material are called pores. Porosity is the amount of empty space within a
material. Permeability describes how well the pores in a material are connected. Which of these
materials would make the most effective aquifer?
A. a material that has high porosity and high permeability
B. a material that has high porosity and low permeability
C. a material that has low porosity and high permeability
D. a material that has low porosity and low permeability

• A
• B
• C
• D

Which is the best example of a pure substance?
A. peanuts
B. milk
C. gold
D. air

• A
• B
• C
• D

Which best describes how ice cores are important to the study of
geologic history?
A. They show unconformities, which signal changes in deposition.
B. They hold index fossils, which are used to date the different ice cores.
C. They contain evidence showing changes in the atmospheric
composition over time.
D. They follow the Law of Superposition, which gives reasons for
extinctions of species.

• A
• B
• C
• D

Which will most likely result if there is increased upwelling in a coastal
area?
A. more aquatic life
B. less nutrients in the water
C. higher water temperatures
D. fewer nitrates

• A
• B
• C
• D

Which factors can have the greatest effect on the health of a river
system?
A. type of soil and salinity
B. nitrate levels and turbidity
C. human consumption and pH
D. natural disasters and tidal changes

• A
• B
• C
• D

If a body of water has high turbidity levels, what can most likely be
concluded?
A. It has a low pH.
B. It is unsafe to drink.
C. It is too hot to drink.
D. It contains a lot of chemicals.

• A
• B
• C
• D

In which oceanic zone do clams and crabs survive by burrowing in the
sand?
A. oceanic
B. intertidal
C. deep ocean
D. open ocean

• A
• B
• C
• D

Scientists find dinosaur fossils in the bottom rock layers of a cliff and
mammal fossils in the middle rock layer of the cliff. Which could best be
concluded from this evidence?
A. Dinosaurs ate plants.
B. Dinosaurs were eaten by the mammals.
C. Dinosaurs lived on Earth before the mammals.
D. Dinosaurs and mammals lived at the same time.

• A
• B
• C
• D

Which shows one example of a physical change and one example of a
chemical change?
A. boiling water and melting wax
B. rusting iron and baking a cake
C. dissolving powder and shredding paper
D. freezing water and burning coal

• A
• B
• C
• D

What do earthquakes tell scientists about the history of the planet?
A. Earth’s climate is constantly changing.
B. The continents of Earth are continually moving.
C. Dinosaurs became extinct about 65 million years ago.
D. The oceans are much deeper today than millions years ago.

• A
• B
• C
• D