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7th Grade Math / Lesson 1: Basic Figures

What will we be learning in this lesson?

  • In this lesson, you will learn about planes, points, lines and rays. These are the basic pieces of all figures.
Vocabulary words are found in this purple color throughout the lesson. Remember to put these in your notebook.


  • A plane is a flat surface that goes on forever. Your paper is an example of part of a plane . The paper actually ends on the four sides. A plane doesn't end.

  • A plane contains an infinite number of points. Infinite means that there are so many that they can not be counted.points are exact locations. It is the fact that there are so many points and they are so close together that we see the image of a plane .

  • A line is a set of points that extends without end in opposite directions.

    Here is an example of a line

    We call this "line AD" or "line DA". The notation for a line is  

    What are some other names for this same line?


  • Other names for this line could be
    Notice the arrow on top and it points both ways. This is because a line continues in both directions. Be sure to use this notation when naming a line.

  • A line segment is part of a line. A line segment actually has two endpoints which means it ends. Unlike lines that go on forever, segments end.

  • Notice that the segment notation does not have the arrows above the letters. This is because the segment does not continue on like the line does.


  • Line segments that are the same length are congruent.

  • Parallel lines are lines that are in the same plane and never intersect each other (they never touch or cross).

  • A ray is part of a line. It only has one endpoint. The other side of the line continues forever.

    This is the "ray AB" Written   Notice the notation looks like the ray. The arrow is above the side that continues. "A" is the endpoint.

    This could also be called


  • An angle is formed by two rays that have the same endpoint.

  • The common endpoint is the vertex.

  • Anywhere that D is used, it could be replaced by C and mean the same thing.

  • Do you know what each of the basic parts of figures are?
  • Can you use the correct notation for naming them?
  • Go back to the classroom to get to your homework and any other items you need to attend to.