Angles
Acute Angle
An angle that measures less than 90 degrees.
Right Triangle
A triangle that has exactly one right angle.
Area
The amount of space inside a flat shape (like a rectangle or square). You can think of it as how many squares fit inside the shape.
Line Segment
A straight path that has a definite beginning and a definite end.
Line Symmetry
A shape can be folded in half so the two sides match exactly.
Obtuse Angle
An angle that measures greater than 90 degrees.
Equilateral Triangle
A triangle where all three sides are the exact same length.
Point
An exact location in space.
Ray
A straight path that starts at one specific point and goes on forever in the other direction.
Intersecting Lines
Lines that cross each other at one point.
Straight Angle
An angle that measures exactly 180 degrees.
Isosceles Triangle
A triangle that has two sides that are the exact same length.
The total distance all the way around a shape.
Line
A straight path that goes on forever in both directions.
Parallel
Lines that run side by side and never meet, no matter how far you extend them.
Right Angle
An angle that measures exactly 90 degrees.
Obtuse Triangle
A triangle that has one obtuse angle.
Dimension
A measurement of how far a shape stretches in a certain direction.
Perpendicular
Lines that meet (cross) and make a perfect corner — a right angle.
Polygon
A flat shape with straight sides that connect to make a closed figure.
Scalene Triangle
A triangle where all three sides are different lengths.
Lines of Symmetry
The fold line in a shape with line symmetry.