Structures
Forces
Machines
100

Because they are not easily bent, _____ are used in buildings. 

columns


100

The force that pulls objects to Earth is _____.

gravity


100
An inclined plane is a _____ machine.

compound

200

Because they are curved, _____ are used to help spread out weight.

arches

200

Opposite poles of a magnet ______.

repel

200

A seesaw is an example of an _____ plane.

inclined

300

The base of any building that keeps it strong is the _____.

foundation

300

Magnets has ____ poles.

two

300

A device that helps make work easier is a ____.

machine

400

A _____ is strong because it has a wide base.

pyramid