Maryland Math 1.GR.B.3
The Standard
Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size).
Maryland College and Career Ready Standards for Mathematics (2025) · REASON WITH SHAPES AND THEIR ATTRIBUTES.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students tell which features make a shape that shape, such as being closed and having three straight sides for a triangle. They ignore color, size, and which way the shape points.
What Mastery Looks Like
- A student picks out triangles even when they are tilted, small, or different colors. They reject open figures and four-sided figures, and explain why using sides and corners.
Common Misconceptions
- Students may think a triangle stops being a triangle when its point faces down. They may use color or size to name a shape, or call an open three-sided drawing a triangle.
How to Assess It
- Show a small tilted triangle, a large upright triangle, an open three-sided figure, and a closed four-sided figure. Ask, "Circle the triangles and tell why the others are not triangles."
Lesson moves
Ways to Teach It
Have students use three craft sticks to build a closed triangle, then separate two ends and decide whether it is still a triangle.
Show a small red triangle and a large blue triangle; ask, "What stays the same even though their colors and sizes change?"
Play triangle detective with cards showing tilted triangles, open figures, and four-sided shapes; students sort them and explain each choice.
Compare a yield sign and a triangular pennant, then ask which parts tell their shape and which parts can change.
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Printable 1.GR.B.3 Worksheet
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