Subtraction is a missing part: 1st grade math lesson

What this lesson shows

12 − 7 = ? becomes 7 + ? = 12. 7 and 5 make 12.

The worked example

The lesson works this one step by step: 12 − 7 = □. Then your kid tries one like it on paper.

The steps

The whole and one part
Ask: plus what?
Count up
The jumps are the answer

Helping at home

Read 12 − 7 as "7 plus what makes 12?". Draw the whole and the part you know, then count up from the part to the whole. The jumps are the answer.

If your kid gets stuck

Ask: the small number plus what makes the big one?

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.OA.B.4
Understand subtraction as an unknown-addend problem. For example, subtract 10 - 8 by finding the number that makes 10 when added to 8.
Common Core 2.OA.B.2
Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.

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

Alabama MA19.1.4, MA19.1.6d, MA19.2.2a
Alaska 1.OA.4, 2.OA.2
Arizona 1.OA.B.4, 2.OA.B.2
Arkansas 1.CAR.5, 2.CAR.1
California 1.OA.B.4, 2.OA.B.2
Colorado 1.OA.B.4, 2.OA.B.2
Connecticut 1.OA.B.4, 2.OA.B.2
Delaware 1.OA.B.4, 2.OA.B.2
District of Columbia 1.OA.B.4, 2.OA.B.2
Florida MA.1.AR.2.1, MA.2.NSO.2.1
Georgia 1.NR.2.3, 2.NR.2.1
Hawaii 1.OA.B.4, 2.OA.B.2
Idaho 1.OA.B.4, 2.OA.B.2
Illinois 1.OA.B.4, 2.OA.B.2
Indiana 1.CA.1
Iowa 1.OA.B.4, 2.OA.B.2
Kansas 1.OA.4, 2.OA.2
Kentucky KY.1.OA.4, KY.2.OA.2
Louisiana 1.OA.B.4, 2.OA.B.2
Maine 1.OA.B.4, 2.OA.B.2
Maryland 1.NOS.C.8, 1.NOS.E.12.b, 1.NOS.E.13.b, 2.NOS.B.6.c, 2.NOS.B.6.a, 2.NOS.B.6.b
Massachusetts 1.OA.B.4, 2.OA.B.2
Michigan 1.OA.B.4, 2.OA.B.2
Minnesota 2.1.2.1, 2.1.2.2
Mississippi 1.OA.4, 2.OA.2
Missouri 2.NBT.B.9, 1.RA.B.6, 2.RA.A.1
Montana MT.1.OA.4, MT.2.OA.2
Nebraska 1.N.5.b, 2.N.4.a
Nevada 1.OA.B.4, 2.OA.B.2
New Hampshire 1.OA.B.4, 2.OA.B.2
New Jersey 1.OA.B.4, 2.OA.B.2
New Mexico 1.OA.B.4, 2.OA.B.2
New York NY-1.OA.4, NY-2.OA.2.a, NY-2.OA.2.b
North Carolina NC.1.OA.4, NC.1.OA.6.d, NC.2.OA.2
North Dakota 2.AR.OA.1
Ohio 1.OA.4, 2.OA.2
Oklahoma 2.N.2.1, 2.N.2.2
Oregon 1.OA.B.4, 2.OA.B.2
Pennsylvania CC.2.2.1.A.2, CC.2.2.2.A.2
Rhode Island 1.OA.B.4, 2.OA.B.2
South Carolina 2.PAFR.1.5
South Dakota 1.OA.B.4, 2.OA.B.2.a, 2.OA.B.2.b
Tennessee 1.OA.B.4, 2.OA.B.2
Texas 111.4.b.4.A
Utah 1.OA.4, 2.OA.2.a, 2.OA.2.b
Vermont 1.OA.B.4, 2.OA.B.2
Virginia 2.CE.1h, 2.CE.1d, 2.CE.1e
Washington 1.OA.B.4, 2.OA.B.2
West Virginia M.1.4, M.2.2
Wisconsin M.1.OA.B.4, M.2.OA.B.2
Wyoming 2.OA.2

Subtraction is a missing part