Counting objects in equal rows by adding
In 2nd grade, children learn to total an array of up to 5 rows and 5 columns by adding the rows, writing equations like 4 + 4 + 4 = 12.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
Try these with your child
These are real questions from our 2nd grade practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Look at the dots arranged in rows. Which addition sentence shows the total number of dots?
- 4 + 3 = 7
- 4 + 4 + 4 = 12
- 3 + 3 + 3 = 9
Why this matters
Rows of equal groups are the picture your child will carry into multiplication. In 3rd grade they will write 3 rows of 4 as 3 × 4 = 12, use the same picture to see why 4 × 3 gives the same total, and later use it to find the area of a rectangle. A child who understands what repeated addition counts will find multiplication facts make sense instead of feeling like a list to memorize.
Where kids can get stuck
- Counting every object one at a time instead of adding rows, then skipping or recounting some in the middle.
- Adding the number of rows to the number of columns, answering 7 for 3 rows of 4.
- Writing the wrong number of addends, such as 4 + 4 for 3 rows of 4, after losing track of the rows.
How you can help
- Look at egg cartons, muffin pans, ice cube trays, or window panes and ask your child how many rows there are, how many are in each row, and how many there are altogether.
- Arrange coins or crackers into rows, such as 4 rows of 5, and ask your child to add the rows aloud. Then turn the array sideways and add the columns.
- Plant pretend gardens with toys or buttons in neat rows, and ask your child to describe the garden with an addition sentence, such as 5 + 5 + 5 = 15.
The kid-friendly video below explains it in a few minutes, and Bobby's Math Club offers free practice that grows with your child.
Kid-friendly explanation
Questions parents ask
Why is my child learning to add rows in arrays?
Arrays show equal groups in a neat, countable way. Adding the rows, such as 5 + 5 + 5 = 15, helps your child see why grouping is faster than counting by ones. This repeated addition is the meaning behind multiplication, which your child will begin in 3rd grade.
Is this multiplication?
Not yet. In 2nd grade, children find array totals by adding equal numbers, like 3 + 3 + 3 + 3 = 12. They are not expected to use the multiplication sign or memorize times tables. This work prepares them for 3rd grade, when 4 rows of 3 is written as 4 × 3 = 12.
Does it matter whether my child adds rows or columns?
No. Both give the same total, and noticing that is valuable. An array with 2 rows of 5 can be added as 5 + 5 or as 2 + 2 + 2 + 2 + 2, and both equal 10. Encourage your child to try both ways and see that the total does not change.
Make learning math fun
Bobby's Math Club turns 2nd grade math practice into something fun to do together.
- Unlimited free practice
- Practice that starts where your child is and grows with them
- Hints when they are stuck, and a celebration when it clicks
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
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Join the clubNote for teachers: This skill is covered by Common Core math standard 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.” Learn how Bobby's Math Club can help your students grow. (Common Core 2.OA.4)