What this lesson shows
Fixes a mistake
A 3 by 4 array has 12 dots. Counting only the outside ring gives 10.
The worked example
The lesson works this one step by step: 3 rows of 4. Then your kid tries one like it on paper.
The steps
- The edge is not all
- Inside dots count
- Add the rows
Helping at home
The dots inside an array count too. Add the rows instead of counting the edge, so no dot is missed.
If your kid gets stuck
Did you count the dots inside?
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