Find every line: 3rd grade math lesson

What this lesson shows

Fixes a mistake

A square has 4 lines of symmetry, not 2.

The worked example

The lesson works this one step by step: a square, a rectangle that is not a square. Then your kid tries one like it on paper.

The steps

Down the middle
Across
Corner to corner, both ways
A square has 4

Helping at home

After down the middle and across, also fold from corner to corner, both ways. Count only the folds where the halves match exactly.

If your kid gets stuck

Try corner to corner too.

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.3.GR.1.3
Georgia 4.GSR.8.1, 4.GSR.8.2, 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

Find every line