Classifying Two-Dimensional Figures

Students are classifying two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size (right, acute, obtuse).  Students will also recognize right triangles as a category, and identify right triangles.

Triangles can be classified by their side lengths:

Equilateral triangles have all sides the same length.

Isosceles triangles have at least two sides the same length.  (Can equilateral triangles also be isosceles triangles?)

Scalene triangles have no sides the same length.,

Triangles can also be classified by their angles.

Equiangular triangles have all angles the same measurement in degrees.

Right triangles have a right angle.

Acute triangles have all angles less than right angles.

Obtuse triangles have one angle greater than a right angle.

Watch this Study Jam to practice/review classifying triangles.

We will also classify quadrilaterals, which are polygons with four sides:

Trapezoids have only one pair of parallel sides.

Parallelograms have two pairs of parallel sides.

Rhombi have all sides the same length.

Rectangles have four right angles.

Squares have all sides the same length and four right angles.  

Watch this Study Jam to practice/review classifying quadrilaterals.

Other polygons may be included where appropriate.

Some figures have a line (or lines) of symmetry.

Watch this Study Jam to practice/review lines of symmetry.

Students will take a quiz on these benchmarks on Tuesday, May 17.