Geometry

angle

A figure formed by two rays that have a common endpoint

Example: 

3D Shapes

Cube: 

obtuse angle

An angle whose measure is greater than 90° and less than 180°

Example: 

Cylinder:

acute angle

An angle that has a measure greater than 0° and less than 90°

Example: 

Prism:

right angle

An angle formed by perpendicular lines, line segments, or rays and with a measure of 90°

Example: 

Edges, Vertices, Faces, Vertex:

Pyramids: 

Square based pyramid:

Protractor:

Protractors usually have two sets of numbers going in opposite directions.

Be careful which one you use!

When in doubt think "should this angle be bigger or smaller than 90° ?"

Triangular based pyramid:

 Types of Lines:

Reflection: (Flip)

Parallel Lines: 

Parallel Lines are lines that never meet!

Rotation: (Turn)

Intersecting Lines: 

Lines that cross each other

Translation: (Slide)

Motion Geometry:

 Perpendicular Lines:

Are lines that cross and make right angles

Clockwise & Counter-Clockwise:

Congruent Figures: 

The same shape and size. 

Two shapes are congruent if you can Turn, Flip and/or Slide one so it fits exactly on the other.

In this example the shapes are congruent (you only need to flip one over and move it a little)

Lines of Symmetry:

Another name for reflection symmetry. One half is the reflection of the other half.

The "Line of Symmetry"  is the imaginary line where you could fold the image and have both halves match exactly.

 Sorting Rules for 2D Shapes