MAFS.2.OA.3.4 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.

Cognitive Complexity Level: 1-Recall

[divider] [/divider] Students are able to… 

  • Identify the number of rows, columns, and total objects in a given array.
  • Create arrays given a certain number of objects and express the total number in a repeated addition equation.
  • Create an array given the dimensions (i.e. 2 rows 4 columns) and explain how to find the total amount (counting, skip counting, repeated addition).

[divider] [/divider] Students are able to…because teachers:

  • Engage students in figuring out the total number of objects in various concrete and pictorial arrays.
  • Pose questions to elicit precise descriptions of arrays (__rows ___ columns).
  • Challenge students to create different arrays using a set amount of tiles or cubes and record descriptions as repeated addition equations.

 [divider] [/divider] Questions to ask students:

  • Ask:  Point to an array and ask how many are there total?  Explain how you know.
    • Sample answer that indicates understanding: “The array has ___  I know because I skip counted by ___.” 
  • Ask: Give students 16 tiles and ask them to make an array.  Then ask them to write an equation to match the array.
    • Sample answer that indicates understanding: 1 row 16 columns; 16 rows 1 column;
      4 rows 4 columns; 2 rows 8 columns; 8 rows 2 columns
      Sample equations: 4 + 4 + 4 + 4 = 16    2+ 2+ 2+ 2+ 2 +2 +2 +2= 16        8 + 8 = 16

[divider] [/divider] Additional Resources:

Additional in depth content knowledge

Video: Use repeated addition to find the total number of objects in an array

https://learnzillion.com/lesson_plans/4821-use-repeated-addition-to-find-the-total-number-of-objects-in-an-array

[divider] [/divider] Sample Formative Assessment Tasks:

[divider] [/divider] Resources/Tasks to Support Your Child at Home:

  • The array game.  Using a dice (with the 6 marked out), have your child roll two numbers.  The first number will represent the number of rows in the rectangular array.  The second number will represent the number of circles/squares/etc in each row.  Have your child create or stamp the model.  Then have them extend to record an equation that relates.  (For example: If your child rolls a 4 and 3, they would make a rectangular array with 4 rows and 3 in each row.  The equation would be 3+3+3+3=12).
  • Khan Academy: Repeated Addition
  • Youtube: Repeated Addition with Arrays