The Coordinate Line (Координатная прямая)
Learn how to locate any number on a line and find the "address" of any point!
What is a Coordinate Line?
A coordinate line (координатная прямая) is a special straight line that helps us show numbers visually. It has three important features:
- Origin (начало координат) — a starting point marked as 0
- Positive direction (положительное направление) — shown by an arrow pointing right
- Unit segment (единичный отрезок) — the distance from 0 to 1, which sets our scale
Key Idea: Every point on the line corresponds to exactly one number, and every number corresponds to exactly one point!
Interactive visualization — available in the full lesson
Coordinate of a Point
The coordinate (координата точки) is the number that corresponds to a point on the line. Think of it as the point's "address"!
How we write it:
- Point A at position 3 is written as A(3)
- Point B at position −2 is written as B(−2)
- The origin is written as O(0)
Positive vs Negative
Positive
Points to the RIGHT of zero
Example: A(5) is 5 units right
Negative
Points to the LEFT of zero
Example: B(−3) is 3 units left
Zero (0) is neither positive nor negative — it's the reference point!