When equal groups line up in a rectangle, it is called an array.
Array is objects arranged in equal rows and columns.
Step 1: Let's Learn
Read it, or press Listen and follow the words.
Rows and columns
Rows go across. Columns go down. Every row holds the same number.
You can read it two ways
3 rows of 4 is 12. Turn your head and it is 4 columns of 3, which is also 12.
An array is equal groups in neat lines
An array arranges objects in rows and columns so every row has the same number and every column has the same number. Egg boxes, window panes, chocolate bars and seating plans are all arrays. The tidiness is what makes them easy to count.
Rows go across, columns go down
A row runs left to right; a column runs top to bottom. An array with 3 rows of 4 has 12 objects. Getting the two words the right way round matters when you describe an array to someone else — the picture changes even though the total does not.
Turning an array
Rotate a 3-by-4 array a quarter turn and it becomes a 4-by-3 array. Rows became columns. The total is still 12, because turning the page does not remove any objects. This is a first look at why 3 × 4 and 4 × 3 give the same answer.
Step 2: Try It Yourself
Tap and try it out.
4 + 4 + 4 = 12
3 rows of 4 makes 12.
Step 3: Watch an Example
One step at a time.
Watch Leo Turn an Array
Leo has an array with 3 rows of 4.
- Step 1
He counts along one row: 4 objects.
Step 4: Your Turn
Practice makes it stick.
The Egg Box
Problem 1 of 2
An egg box has 2 rows of 5. How many eggs does it hold?
eggs
The Seating Plan
Problem 2 of 2
A room has 4 rows of 5 chairs. How many chairs?
chairs
Read the Array
1 of 4
3 rows of 3. How many in all?
2 of 4
5 rows of 2. How many in all?
3 of 4
2 rows of 4. How many in all?
4 of 4
4 rows of 4. How many in all?
Step 5: Quick Check
Show what you know.
Question 1 of 2
3 rows of 5. How many in all?
Question 2 of 2
Does 3 rows of 4 give the same total as 4 rows of 3?
What You Learned
- An array is equal groups in rows and columns.
- Rows go across, columns go down.
- 3 rows of 4 and 4 rows of 3 both give 12.