Fifteen is not 51: 1st grade math lesson

What this lesson shows

Fixes a mistake

Fifteen says the ones first, but writes the ten first: 1 ten, 5 ones, 15.

The worked example

The lesson works this one step by step: 15. Then your kid tries one like it on paper.

The steps

A teen is 1 ten and some ones
Write the 1 first
Then the ones

Helping at home

Say the number, then show it as 1 ten and some ones. Write the ten first, then the ones, whatever the name says first.

If your kid gets stuck

The ten is written first.

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 1.NBT.B.2b
The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.

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

Alabama MA19.1.11a, MA19.1.11b
Alaska 1.CC.4, 1.NBT.2.b
Arizona 1.NBT.B.2.b
Arkansas 1.NPV.3, 1.NPV.4
California 1.NBT.B.2
Colorado 1.NBT.B.2.b
Connecticut 1.NBT.B.2
Delaware 1.NBT.B.2
District of Columbia 1.NBT.B.2
Florida MA.1.NSO.1.2
Georgia 1.NR.1.2
Hawaii 1.NBT.B.2
Idaho 1.NBT.B.2.b
Illinois 1.NBT.B.2
Indiana 1.NS.2
Iowa 1.NBT.B.2.b
Kansas 1.NBT.2.b, 1.NBT.2.d
Kentucky KY.1.NBT.2.b
Louisiana 1.NBT.B.2.b
Maine 1.NBT.B.2b
Maryland 1.NOS.B.3.a, 1.NOS.B.3.b
Massachusetts 1.NBT.B.2.b
Michigan 1.NBT.B.2
Minnesota 1.1.1.1, 1.1.1.2
Mississippi 1.NBT.2.b
Missouri 1.NBT.A.2
Montana MT.1.NBT.1, MT.1.NBT.2
Nebraska 1.N.1.a, 1.N.3.a
Nevada 1.NBT.B.2
New Hampshire 1.NBT.B.2
New Jersey 1.NBT.B.2b
New Mexico 1.NBT.B.2
New York NY-1.NBT.2.b
North Carolina NC.1.NBT.2.b
North Dakota 1.NO.NBT.1
Ohio 1.NBT.2
Oklahoma 1.N.1.2, 1.N.1.3
Oregon 1.NBT.B.2
Pennsylvania CC.2.1.1.B.2
Rhode Island 1.NBT.B.2.b
South Carolina 1.NR.1.2, 1.NR.1.1
South Dakota 1.NBT.B.2.b
Tennessee 1.NBT.B.3
Texas 111.3.b.2.B, 111.3.b.2.C
Utah 1.NBT.2.b
Vermont 1.NBT.B.2
Virginia K.NS.1j, 1.NS.1e, 1.NS.2c, 1.NS.2d
Washington 1.NBT.B.2
West Virginia M.1.10
Wisconsin M.1.NBT.B.2
Wyoming 1.NBT.2b, 1.NBTP.2.B

Fifteen is not 51