Don’t flip the ones: 1st grade math lesson

What this lesson shows

Fixes a mistake

12 − 5 takes 5 from 12. Taking 2 from 5 gives 3, the wrong answer. Open the ten: 7.

The worked example

The lesson works this one step by step: 12 − 5 = □. Then your kid tries one like it on paper.

The steps

Take the ones
Open the ten for the rest
Never flip the numbers

Helping at home

Always take the second number from the first. When there are not enough ones, take the ones there are, then open the ten for the rest.

If your kid gets stuck

Take the ones first, then open the ten.

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.C.6
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).

Matches standards in 49 statesSee each state's code

Alabama MA19.1.6a, MA19.1.6b, MA19.1.6c, MA19.1.6d, MA19.1.6e
Alaska 1.OA.6
Arkansas 1.CAR.1, 1.CAR.2
California 1.OA.C.6
Colorado 1.OA.C.6
Connecticut 1.OA.C.6
Delaware 1.OA.C.6
District of Columbia 1.OA.C.6
Florida MA.1.NSO.2.1, MA.1.NSO.2.2
Georgia 1.NR.2.1, 1.NR.2.2, 1.NR.2.4
Hawaii 1.OA.C.6
Idaho 1.OA.C.6
Illinois 1.OA.C.6
Indiana 1.CA.1
Iowa 1.OA.C.6, 1.OA.IA.C.2, 1.OA.IA.C.1.b
Kansas 1.OA.6
Kentucky KY.1.OA.6.b
Louisiana 1.OA.C.6
Maine 1.OA.C.6
Maryland 1.NOS.E.10.a, 1.NOS.E.10.b, 1.NOS.E.12.a, 1.NOS.E.12.b, 1.NOS.E.13.a, 1.NOS.E.13.b, 2.NOS.B.6.a, 2.NOS.B.6.b
Massachusetts 1.OA.C.6
Michigan 1.OA.C.6
Minnesota 1.1.2.2, 2.1.2.1
Mississippi 1.OA.6
Missouri 1.RA.C.7, 1.RA.C.8
Montana MT.1.OA.3, MT.1.OA.6, MT.1.OA.7
Nebraska 1.N.4.a, 1.N.4.b
Nevada 1.OA.C.6
New Hampshire 1.OA.C.6
New Jersey 1.OA.C.6
New Mexico 1.OA.C.6
New York NY-1.OA.6.a
North Carolina NC.1.OA.9, NC.1.OA.6.a, NC.1.OA.6.b, NC.1.OA.6.c, NC.1.OA.6.d, NC.1.OA.6.e, NC.1.OA.6.f
North Dakota 1.AR.OA.1, 1.AR.OA.2, 1.AR.OA.3
Ohio 1.OA.6
Oklahoma 1.N.2.3
Oregon 1.OA.C.6
Rhode Island 1.OA.C.6
South Carolina 1.PAFR.1.4, 1.PAFR.1.2
South Dakota 1.OA.C.6
Tennessee 1.OA.C.5, 1.OA.C.6
Texas 111.3.b.3.D, 111.3.b.3.E
Utah 1.OA.6.a, 1.OA.6.b
Vermont 1.OA.C.6
Virginia 1.CE.1a, 1.CE.1b, 1.CE.1c, 1.CE.1d, 1.CE.1e
Washington 1.OA.C.6
West Virginia M.1.6
Wisconsin M.1.OA.C.6
Wyoming 1.OA.6

Don’t flip the ones