Geometry Lessons for Grade 4
Draw points, lines, rays, and angles; measure angles with a protractor; identify symmetry; and classify figures from parallel or perpendicular sides. These lessons give each idea room for an interactive diagram, worked examples, and hands-on exploration.
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Opposite Rays
Opposite rays share an endpoint and form a straight line.
Open lesson →Midpoint
The midpoint divides a segment into two equal parts.
Open lesson →Segment Bisector
A segment bisector passes through a segment's midpoint.
Open lesson →Parts of an Angle
An angle is made from a vertex and two sides that are rays.
Open lesson →Acute Angle
An acute angle measures less than 90 degrees.
Open lesson →Right Angle
A right angle measures exactly 90 degrees.
Open lesson →Obtuse Angle
An obtuse angle measures more than 90 degrees and less than 180 degrees.
Open lesson →Straight Angle
A straight angle measures exactly 180 degrees.
Open lesson →Parallel Lines
Parallel lines stay the same distance apart and never intersect.
Open lesson →Perpendicular Lines
Perpendicular lines intersect to form right angles.
Open lesson →Acute Triangle
An acute triangle has three angles less than 90 degrees.
Open lesson →Right Triangle
A right triangle has one angle measuring 90 degrees.
Open lesson →Obtuse Triangle
An obtuse triangle has one angle greater than 90 degrees.
Open lesson →Equiangular Triangle
An equiangular triangle has three equal angles.
Open lesson →Parallelogram
A parallelogram is a quadrilateral with both pairs of opposite sides parallel.
Open lesson →Rhombus
A rhombus is a quadrilateral with four equal sides.
Open lesson →Trapezoid
A trapezoid has at least one pair of parallel sides.
Open lesson →Kite
A kite has two pairs of adjacent equal sides.
Open lesson →Center of a Circle
The center is the point equally distant from every point on the circle.
Open lesson →Radius
A radius is a segment from the center of a circle to a point on the circle.
Open lesson →Diameter
A diameter is a chord passing through the center and equals two radii.
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