A longer decimal isn’t bigger: 4th grade math lesson

What this lesson shows

Fixes a mistake

0.4 is more than 0.38: 0.4 is the same as 0.40.

The worked example

The lesson works this one step by step: 0.4 ○ 0.38. Then your kid tries one like it on paper.

The steps

Longer is not bigger
A 0 at the end changes nothing
Compare in hundredths
Or compare from the left

Helping at home

Before choosing a sign, add a 0 so both decimals have hundredths, then compare. Or compare from the left: the first place that differs decides. Never decide by how many digits there are.

If your kid gets stuck

Add a 0 so both have hundredths.

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.NF.C.7
Compare two decimals to hundredths by reasoning about their size. Recognize that comparisons are valid only when the two decimals refer to the same whole. Record the results of comparisons with the symbols >, =, or <, and justify the conclusions, e.g., by using a visual model.
Common Core 5.NBT.A.3b
Compare two decimals to thousandths based on meanings of the digits in each place, using >, =, and < symbols to record the results of comparisons.

Matches a standard in all 50 states and DCSee each state's code

Alabama MA19.4.19, MA19.5.4b
Alaska 4.NF.7, 5.NBT.3.b
Arizona 4.NF.C.7, 5.NBT.A.3.b
Arkansas 4.NPV.6, 5.NPV.5
California 4.NF.C.7, 5.NBT.A.3
Colorado 4.NF.C.7, 5.NBT.A.3.b
Connecticut 4.NF.C.7, 5.NBT.A.3
Delaware 4.NF.C.7, 5.NBT.A.3
District of Columbia 4.NF.C.7, 5.NBT.A.3
Florida MA.4.NSO.1.5, MA.5.NSO.1.4
Georgia 4.NR.5.3, 5.NR.4.2
Hawaii 4.NF.C.7, 5.NBT.A.3
Idaho 4.NF.C.7.a, 4.NF.C.7.b, 5.NBT.A.3.b
Illinois 4.NF.C.7, 5.NBT.A.3
Indiana 4.NS.6, 5.NS.1
Iowa 4.NF.C.7, 5.NBT.A.3.b
Kansas 4.NF.7, 5.NBT.3.b
Kentucky KY.4.NF.7.a, KY.4.NF.7.b, KY.4.NF.7.c, KY.5.NBT.3.a, KY.5.NBT.3.b
Louisiana 4.NF.C.7, 5.NBT.A.3.b
Maine 4.NF.C.7, 5.NBT.A.3b
Maryland 4.NOS.F.16, 5.NOS.A.3.c
Massachusetts 4.NF.C.7, 5.NBT.A.3.b
Michigan 4.NF.C.7, 5.NBT.A.3
Minnesota 4.1.2.5, 4.1.2.4, 5.1.2.1, 5.1.2.3
Mississippi 4.NF.7, 5.NBT.3.b
Missouri 4.NF.C.12, 5.NBT.A.2, 5.NF.A.3
Montana MT.4.NF.7, 4.D1.11, MT.5.NBT.3.b, 5.D1.1
Nebraska 4.N.1.b, 5.N.2.b
Nevada 4.NF.C.7, 5.NBT.A.3
New Hampshire 4.NF.C.7, 5.NBT.A.3
New Jersey 4.NF.C.7, 5.NBT.A.3b
New Mexico 4.NF.C.7, 5.NBT.A.3
New York NY-4.NF.7, NY-5.NBT.3.b
North Carolina NC.4.NF.7, NC.5.NBT.3.b
North Dakota 4.NO.NBT.2, 5.NO.NBT.2
Ohio 4.NF.7, 5.NBT.3.b
Oklahoma 4.N.3.8, 4.N.3.9, 5.N.1.3
Oregon 4.NF.C.7, 5.NBT.A.3
Pennsylvania CC.2.1.4.C.3, CC.2.1.5.B.1
Rhode Island 4.NF.C.7, 5.NBT.A.3.b
South Carolina 4.NR.2.2, 5.NR.1.1
South Dakota 4.NF.C.7, 5.NBT.A.3.b
Tennessee 4.NF.C.6, 4.NF.C.7
Texas 111.6.b.2.F, 111.6.b.2.H, 111.6.b.3.G, 111.7.b.2.B
Utah 4.NF.7, 5.NBT.3.b
Vermont 4.NF.C.7, 5.NBT.A.3
Virginia 4.NS.4e, 5.NS.1d
Washington 4.NF.C.7, 5.NBT.A.3
West Virginia M.4.18, M.5.6
Wisconsin M.4.NF.C.7, M.5.NBT.A.3
Wyoming 4.NF.7

A longer decimal isn’t bigger