Maryland Math 2.GR.B.6

Math2nd GradeGeometric Reasoning and Measurement

The Standard

Explain that a line of symmetry for a two-dimensional figure is a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.

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 decide whether a flat shape can fold into two matching halves. They draw the fold lines and check that the edges and corners line up.
What Mastery Looks Like: Students draw four symmetry lines on a square and two on a rectangle that is not a square. They explain why a diagonal does not work on that rectangle.
Common Misconceptions: Some students think any line through the center works, including a diagonal across a long rectangle. Others look only for vertical lines or think equal areas count even when the edges do not line up.
How to Assess It: Show a square and a long rectangle. Ask, 'Draw every line you could fold along to make matching halves. Why does a diagonal not work on the rectangle?'

Lesson moves

Ways to Teach It

Give pairs paper squares, long rectangles, and lopsided cutouts; have them fold each shape and trace every crease that makes matching halves.
Show a long rectangle with a diagonal drawn; ask, 'Would the corners meet if we folded here? How do you know?'
Hand out shape cards with marked lines; have students sort them into 'matches when folded' and 'does not match' piles.
Sketch a rectangular classroom window and draw each line that would make its outline match when folded.

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