Mississippi Math 4.G.2

Math4th GradeGeometry (G) Draw and Identify Lines and Angles, and Classify Shapes by Properties of their Lines and Angles

The Standard

Classify 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. Categorize triangles by sides and angles (equilateral, isosceles, right, and scalene).

2025 Mississippi College- and Career-Readiness Standards for Mathematics · Geometric Measurement: Understand Concepts of Angle and Measure Angles

Teacher's field guide

What This Standard Means

What Students Need to Do: Students sort flat shapes by whether they have parallel sides, perpendicular sides, or angles of a given size. They name triangles by their side lengths and angles.
What Mastery Looks Like: A student can mark parallel sides and right angles even when a shape is turned. They can use side marks and angle measures to explain why a triangle is both isosceles and right.
Common Misconceptions: Students may think slanted lines cannot be perpendicular, even when they meet at 90°. They may give a triangle only one name or guess that sides are equal without checking.
How to Assess It: Show a square and a triangle with two equal sides marked and a right angle between them. Ask: “Which shapes have parallel sides? Which have perpendicular sides? Name the triangle by its sides and its angle.”

Lesson moves

Ways to Teach It

Give pairs paper triangles, a ruler, and a square corner; have them mark equal sides and right angles, then sort the triangles.
Show a right isosceles triangle and ask, “Can this triangle have two names? What evidence supports each name?”
Play a card sort with marked triangles; students match each card to a side label and an angle label.
Use a photo of a window and a shelf bracket; have students trace parallel edges, perpendicular edges, and a right triangle.

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