1.2 Points, Line Segments,
Lines and Rays…OH MY!
Mental Math
Solve these subtraction problems.
Write your answer on your slate.
9 – 0 =
12 – 6 =
16 – 9 =
17 – 8 =
90 – 40 =
140 – 70 =
Math Message
Read SRB pages 88 and 89.
In your Math Notebook, please list three places
where geometry can be found in our world.
Be ready to share.
Reviewing Points, Line Segments,
Lines and Rays
A
B
When you connect
two points using a
straightedge, you
create a
line segment
points
Points, Endpoints and Line
Segments
endpoint
A
endpoint
B
line segment
• letters are often used to name a line segment
• ONE name for this line segment is “line segment AB”
• A short way to write “line segment AB” is AB
• Another name for this line segment is “line segment BA”
• What is the short way to write “line segment BA?”
Stop and Chat!
endpoint
endpoint
A
B
How would you describe a line segment to
someone who has never seen one before?
What are some examples of line segments
that we can find in the world?
EXAMPLE: part of a spider web
Lines
point
A
point
B
lines
• extending line segment AB in both directions and drawing
an arrowhead at each end makes a LINE
• This line is called “line AB” or “line BA”
• A short way to write the names of these lines is
AB or BA
Stop and Chat!
point
point
A
B
How is a line different from a line segment?
What are some examples of lines that we can
find in the world?
EXAMPLE: The horizon in a landscape
Ray
endpoint
point
C
D
rays
• line segment that goes on without end in only ONE
direction
• Point C is the ENDPOINT of the ray CD
• The letter that names the ENDPOINT is ALWAYS
written first.
Short way to write the name is CD
Stop, Try and Chat!
endpoint
C
point
D
Short way to write the name is CD
On your slate, draw ray ZY. Remember
that the endpoint of the ray is ALWAYS
written first.
What are some examples of lines that
we can find in the world?
Example: Hitting a golf ball
Let’s Review!
Is it ever possible to draw all of a line?
All of a line segment?
All of a ray?
How many line segments can you name using
the points marked on this line?
How many rays can you name?
Independent work MJ page 4
You can use
SRB pages 90
and 91 to help
you!
Wrap it UP!
In your Math Notebook…
Draw and label YX
Draw and label HG
Draw and label VB
Addition Top-It
Tonight’s Homework
Math Boxes