Curriculum placement
Grade 2. This describes the skill, not a learner estimate.
Rectangular arrays
Count rectangular arrays using equal rows
Problem types
- Count a unit array
- Add the rows of an array
- Equation for an array
- Array for an equation
- Both equations for an array
- Build an array and its addition sentence
- Partition a rectangle from edge marks
- Choose the equal-square partition
Builds on
- Skip-counting
- Addition and subtraction facts within 5 · Useful idea
The total in a small array is found by adding its rows, and the sums stay within the facts to 5.
Leads to
- Measuring area by counting squares
- Multiplication as equal groups
- Area of a rectangle
- Probability of compound events · See it applied
The rows and columns of an array count the outcomes of two choices, which is the counting principle.
Related skills
- Graphing in the first quadrant · Related idea
Points on a grid sit in rows and columns like the objects of an array, and a pair of numbers names the row and column.
- Data arranged in a matrix · Related idea
A table of rows and columns is an array of numbers, and its entries are read by row and column.
- Telling time to five minutes · Shared foundations
Open the interactive map to explore lessons and skill connections.