Lines of symmetry: 3rd grade math lesson

What this lesson shows

Fold the letter H: both halves match, twice.

The worked example

The lesson works this one step by step: the letter H, the letter T, the letter F. Then your kid tries one like it on paper.

The steps

Fold so the halves match
Try every way
H has 2, T has 1
F has none

Helping at home

Draw the figure on paper and fold it. If the two halves match exactly, the fold is a line of symmetry: draw it as a dashed line. Try down the middle, across, and corner to corner.

If your kid gets stuck

Fold it: do the halves match?

Watch it with Lux

With Lux, this lesson is a narrated video and a printed page your kid works on. Then Lux helps with the same math on their own worksheet, one question at a time.

See how Lux works

Standards

Common Core 4.G.A.3
Recognize a line of symmetry for a two-dimensional figure as 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.

Matches standards in 47 statesSee each state's code

Alabama MA19.4.29a
Alaska 4.G.3
Arizona 4.G.A.3
Arkansas 4.GM.6
California 4.G.A.3
Colorado 4.G.A.3
Connecticut 4.G.A.3
Delaware 4.G.A.3
District of Columbia 4.G.A.3
Florida MA.2.GR.1.3, MA.3.GR.1.3
Georgia 4.GSR.8.1, 4.GSR.8.2, 2.GSR.7.2, 3.GSR.6.3
Hawaii 4.G.A.3
Idaho 4.G.A.3
Illinois 4.G.A.3
Indiana 4.G.2
Iowa 4.G.A.3
Kansas 4.G.3
Kentucky KY.4.G.3.a, KY.4.G.3.b
Louisiana 4.G.A.3
Maine 4.G.A.3
Maryland 2.GR.B.6
Massachusetts 4.G.A.3
Michigan 4.G.A.3
Minnesota 4.3.3.2
Mississippi 4.G.3
Missouri 4.GM.A.3
Montana MT.4.G.3, 4.D1.20
Nebraska 4.G.1.d
Nevada 4.G.A.3
New Hampshire 4.G.A.3
New Jersey 4.G.A.3
New Mexico 4.G.A.3
New York NY-4.G.3
North Carolina NC.4.G.3
North Dakota 4.GM.G.3, 3.GM.G.3
Oregon 4.GM.A.3
Pennsylvania CC.2.3.4.A.3
Rhode Island 4.G.A.3
South Dakota 4.G.A.3
Tennessee 4.G.A.3
Texas 111.6.b.6.B
Utah 4.G.3
Vermont 4.G.A.3
Virginia 2.MG.3a, 2.MG.3c, 2.MG.3b
Washington 4.G.A.3
West Virginia M.4.28
Wisconsin M.4.G.A.3

Lines of symmetry