Arrays for multiplication (age 7+)
Use addition to find the total number of objects arranged in rectangular arrays with up to 5 rows and 5 columns; write an equation to express the total as a sum of equal addends
What a learner can do afterwards
- Count objects in a 3×4 array and write 4 + 4 + 4 = 12
- Explain that each row has the same number of objects so the total can be found by repeated addition
- Draw a rectangular array to model a given repeated-addition equation
1 · Read
You already know what an array looks like, and you know how to add the same number again and again. Now put those together. In an array, every row has the same number of objects, so you can add up the rows to get the total, and write it as an equation.
Mia lines up 4 rows of 5 buttons. Each row has 5 buttons, so she adds 5 four times: 5 + 5 + 5 + 5 = 20 buttons.
The number of rows tells you how many addends to write. The number of objects in each row tells you what number to add each time.
Count the rows, then add that many equal groups to write the equation.
Readings 'Matching an array to its addition', 'Equal rows', 'Arrays around you' and 'Three ways to show one total' are original to this dataset. All 9 extra questions are original to this dataset.
2 · Watch
Take it off screen
Where it sits
17 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.