There are 3 Undefined Terms:
1. Points
2. Lines
3. Planes
Why are they Undefined?
Points, lines and planes are considered to be undefined terms
because they are only explained using examples and descriptions
Undefined Terms
A Point is simply a location
Model:
How is it Drawn? As a dot
How is it Named?
 Using a capital letter
 Point P
⦁P
Fact:
A point has neither shape nor size
Point
A Line is made up of points and has no thickness or width
Model:
How is it Drawn?
With an arrowhead at each end
How is it Named?
 The letters representing two points on
the line or a lowercase script letter
 Line n, Line AB, Line BA, AB, BA
Line
A
⦁
B
⦁
n
Fact:
There is exactly one line
through any two points
A Plane is a flat surface made up of points
It has no depth and extends indefinitely in all directions
Model:
How is it Drawn?
As a shaded, slanted 4-sided figure
How is it Named?
 A capital script letter or by the letters
naming three noncollinear points
 Plane T, Plane XYZ, Plane XZY, Plane YXZ,
Plane YZX, Plane ZXY, Plane ZYX
Plane
X⦁
Z⦁
⦁Y
T
Fact:
There is exactly one plane
through any three
noncollinear points
Points that lie on the same plane are Coplanar
Not Coplanar:
Coplanar:
⦁
B⦁
A
⦁
C
B
D
A
Coplanar
⦁
⦁
⦁
D
C
Points that lie on the same line are Collinear
Not Collinear:
Collinear:
C
⦁
C
d
⦁
B
A
⦁
⦁
A
B
⦁
Collinear
⦁
d
Chapter 1 Section 1
Vocabulary
Chapter 1 Section 1 Vocabulary Flip Chart
Assembly Instructions:
1. Cut all papers along the dashed line that bisects the paper.
2. Position the “Coplanar” paper so that the bottom corners line up with the bottom
corners of the cardstock and the writing is on the side you can see.
3. Tape the top of the “Coplanar” paper to the cardstock.
4. Position the “Plane” paper so that the bottom of the paper lines up with the dotted
line on the “Coplanar” paper and the writing is on the side you can see.
5. Tape the top of the “Plane” paper to the cardstock.
6. Continue attaching papers to the cardstock in the following order: Coplanar, Plane,
Collinear, Line, Point, Undefined Terms, Chapter 1 Section 1 Vocabulary.
When complete, your flipchart should look like:
Chapter 1 Section 1
Vocabulary
Undefined Terms
Point
Line
Collinear
Plane
Coplanar