4th Grade Lines, Rays and Classifying Shapes Lesson (Free PDF)
A point is an exact spot. A line goes on forever in both directions, a ray has one endpoint and goes on forever one way, and a line segment has two endpoints. Lines can be parallel or perpendicular. Shapes are sorted by their parallel sides and by right, acute, or obtuse angles.
Grade 4 · Common Core State Standards: 4.G.A.1, 4.G.A.2
- A line segment has two endpoints; a ray has one; a line has none.
- Parallel lines never meet, and perpendicular lines meet at a right angle (90°).
- Right angles are 90°, acute angles are less than 90°, and obtuse angles are greater than 90°.
- A right triangle has exactly one right angle.
- Quadrilaterals are sorted by pairs of parallel sides and by right angles.
What are points, lines, rays, and segments?
Geometry starts with a few simple ideas. A point marks an exact place. A line is straight and never ends. A ray starts at one point and goes on forever in one direction. A line segment is a piece of a line with two endpoints, like a pencil drawn on paper.
What are parallel and perpendicular lines?
Look at two lines. If they stay the same distance apart and never meet, they are parallel, like the rails of a train track. If they meet and form a right angle, they are perpendicular, like the edges of a book corner.
A right angle measures exactly 90°. An acute angle is smaller than 90°. An obtuse angle is bigger than 90° but smaller than 180°.
How do you classify triangles?
Look at the biggest angle of the triangle. If all three angles are acute, it is an acute triangle. If one angle is a right angle, it is a right triangle. If one angle is obtuse, it is an obtuse triangle. A triangle can have only one right or obtuse angle.
How do you classify quadrilaterals?
A quadrilateral has four sides. Count the pairs of parallel sides and the right angles. Little arrows mean sides are parallel, and a little square means a right angle.
Example. Maya draws a shape with 4 sides, 2 pairs of parallel sides, and 4 right angles. What is it?
- Four sides means it is a quadrilateral.
- Two pairs of parallel sides means opposite sides are parallel.
- Four right angles means it is a rectangle (a square if all sides are equal).
Questions about lines, rays and classifying shapes
What is the difference between a line, a ray, and a segment?
A line goes on forever in both directions. A ray has one endpoint and goes on forever in one direction. A line segment has two endpoints and a fixed length.
How can you tell if two lines are perpendicular?
Perpendicular lines meet at a right angle, which is exactly 90 degrees. You can check with the corner of a sheet of paper or with a protractor.
What is a right triangle?
A right triangle is a triangle with one right angle (90 degrees). The other two angles are both acute. The corner is often marked with a small square.
How many pairs of parallel sides does a parallelogram have?
A parallelogram has two pairs of parallel sides, because both pairs of opposite sides are parallel. A rectangle and a square are special parallelograms with four right angles.
Can a triangle have two right angles?
No. Two right angles would use up 180 degrees, and the third side could never close the triangle. A triangle has at most one right angle or one obtuse angle.
All Grade 4 chapters: Grade 4 math.
Print this page
Download PDFDownload the 4th Grade Lines, Rays and Classifying Shapes Lesson (PDF, 56 KB)More 4th Grade math
Lessons
See all
Worksheets
See all
Tests
See all
Comparing Fractions Test with Point Values- Factors, Multiples, Prime and Composite Test with Point Values
- Rounding Whole Numbers Test with Point Values
- Tenths, Hundredths and Decimal Notation Test with Point Values
- Measuring and Drawing Angles Test with Point Values
- Multiplicative Comparison Test with Point Values
