What this lesson shows
□ − 7 = 9: a bar for the whole, split into 9 and 7. The whole is 16.
The worked example
The lesson works this one step by step: □ − 7 = 9. Then your kid tries one like it on paper.
The steps
- The two parts
- Add them for the whole
- Check it
Helping at home
Draw a bar for the whole with a box in it, and the two numbers you know as its parts. The whole is the parts together. Check by putting it back.
If your kid gets stuck
Which number is the whole?
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.
Standards
- Common Core 1.OA.D.8
Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = _ - 3, 6 + 6 = _.
Matches standards in 46 statesSee each state's code
- Alabama MA19.1.8
- Alaska 1.OA.8
- Arizona 1.OA.D.8
- Arkansas 1.CAR.9
- California 1.OA.D.8
- Colorado 1.OA.D.8
- Connecticut 1.OA.D.8
- Delaware 1.OA.D.8
- District of Columbia 1.OA.D.8
- Florida MA.1.AR.2.3
- Georgia 1.NR.2.6
- Hawaii 1.OA.D.8
- Idaho 1.OA.D.8
- Illinois 1.OA.D.8
- Iowa 1.OA.D.8
- Kansas 1.OA.8
- Kentucky KY.1.OA.8
- Louisiana 1.OA.D.8
- Maine 1.OA.D.8
- Maryland 1.AT.A.3
- Massachusetts 1.OA.D.8
- Michigan 1.OA.D.8
- Minnesota 1.2.2.3
- Mississippi 1.OA.8
- Missouri 1.RA.A.4
- Montana MT.1.OA.9
- Nebraska 1.N.5.c
- Nevada 1.OA.D.8
- New Hampshire 1.OA.D.8
- New Jersey 1.OA.D.8
- New Mexico 1.OA.D.8
- New York NY-1.OA.8
- North Carolina NC.1.OA.8
- Ohio 1.OA.8
- Oklahoma 3.A.2.1
- Oregon 1.OA.D.8
- Rhode Island 1.OA.D.8
- South Carolina 2.PAFR.1.7, 1.PAFR.1.6
- South Dakota 1.OA.D.8
- Tennessee 1.OA.D.8
- Texas 111.3.b.3.B, 111.3.b.5.F
- Utah 1.OA.8
- Vermont 1.OA.D.8
- Virginia 1.CE.1g, 2.CE.1g
- Washington 1.OA.D.8
- West Virginia M.1.8