What this lesson shows
The 20 chairs as 4 rows of 5. Turned, they are 5 rows of 4, still 20.
The worked example
The lesson works this one step by step: 4 rows of 5. Then your kid tries one like it on paper.
The steps
- Add one row at a time
- Turn it
- Rows and columns swap
- Same total
Helping at home
Add the same number once for every row. Turn the array a quarter turn: the rows and the number in each swap, and the total stays the same.
If your kid gets stuck
How many rows? How many in each?
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 2.OA.C.4
Use addition to find the total number of objects arranged in rectangular arrays with up to 5 rows and up to 5 columns; write an equation to express the total as a sum of equal addends.
Matches standards in 48 statesSee each state's code
- Alabama MA19.2.4a
- Alaska 2.OA.4
- Arizona 2.OA.C.4
- Arkansas 2.CAR.5
- California 2.OA.C.4
- Colorado 2.OA.C.4
- Connecticut 2.OA.C.4
- Delaware 2.OA.C.4
- District of Columbia 2.OA.C.4
- Florida MA.2.AR.3.2
- Georgia 2.NR.3.2
- Hawaii 2.OA.C.4
- Idaho 2.OA.C.4
- Illinois 2.OA.C.4
- Iowa 2.OA.C.4
- Kansas 2.OA.4
- Kentucky KY.2.OA.4
- Louisiana 2.OA.C.4
- Maine 2.OA.C.4
- Maryland 2.NOS.A.2.b
- Massachusetts 2.OA.C.4
- Michigan 2.OA.C.4
- Minnesota 2.2.1.1
- Mississippi 2.OA.4
- Missouri 2.RA.B.3
- Montana MT.2.OA.4
- Nebraska 2.N.5.c
- Nevada 2.OA.C.4
- New Hampshire 2.OA.C.4
- New Jersey 2.OA.C.4
- New Mexico 2.OA.C.4
- New York NY-2.OA.4
- North Carolina NC.2.OA.4
- North Dakota 2.AR.OA.5
- Ohio 2.OA.4
- Oklahoma 2.N.2.6
- Oregon 2.OA.C.4, 3.OA.A.1
- Pennsylvania CC.2.2.2.A.3
- Rhode Island 2.OA.C.4
- South Carolina 2.PAFR.1.9
- South Dakota 2.OA.C.4
- Tennessee 2.OA.C.4
- Texas 111.4.b.6.A
- Utah 2.OA.4
- Vermont 2.OA.C.4
- Washington 2.OA.C.4
- West Virginia M.2.5
- Wisconsin M.2.OA.C.4