Ten more changes the tens: 1st grade math lesson

What this lesson shows

Fixes a mistake

Ten more than 23 is 33, not 24. The tens digit moves, the ones stay.

The worked example

The lesson works this one step by step: 23. Then your kid tries one like it on paper.

The steps

One more changes the ones
Ten more changes the tens
One row down

Helping at home

Ten more adds a whole ten: the tens digit goes up by one and the ones digit stays. On a 120 chart, it is one row down.

If your kid gets stuck

Which digit changes?

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.C.5
Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.

Matches standards in 48 statesSee each state's code

Alabama MA19.1.14
Alaska 1.NBT.5
Arizona 1.NBT.C.5
Arkansas 1.NPV.6
California 1.NBT.C.5
Colorado 1.NBT.C.5
Connecticut 1.NBT.C.5
Delaware 1.NBT.C.5
District of Columbia 1.NBT.C.5
Florida MA.1.NSO.2.3
Georgia K.NR.1.3, 1.NR.5.2
Hawaii 1.NBT.C.5
Idaho 1.NBT.C.5
Illinois 1.NBT.C.5
Iowa 1.NBT.C.5
Kansas 1.NBT.5
Kentucky KY.1.NBT.5
Louisiana 1.NBT.C.5
Maine 1.NBT.C.5
Maryland 1.NOS.A.1.b, 1.NOS.E.11
Massachusetts 1.NBT.C.5
Michigan 1.NBT.C.5
Minnesota K.1.1.4, 1.1.1.4
Mississippi 1.NBT.5
Missouri 1.NBT.A.4, 1.NBT.B.6
Montana MT.1.NBT.5
Nebraska 1.N.4.d
Nevada 1.NBT.C.5
New Hampshire 1.NBT.C.5
New Jersey 1.NBT.C.5
New Mexico 1.NBT.C.5
New York NY-1.NBT.5
North Carolina NC.1.NBT.5
North Dakota 1.NO.CC.2, 1.NO.NBT.5
Ohio 1.NBT.5
Oklahoma K.N.1.7, 1.N.1.6
Oregon 1.NBT.C.5
Pennsylvania CC.2.1.1.B.3
Rhode Island 1.NBT.C.5
South Carolina 1.NR.1.4
South Dakota 1.NBT.C.5
Tennessee 1.NBT.C.6
Texas 111.2.b.2.F, 111.3.b.5.C
Utah 1.NBT.5
Vermont 1.NBT.C.5
Washington 1.NBT.C.5
West Virginia M.1.13
Wisconsin M.1.NBT.C.5

Ten more changes the tens