Unit 8, Lesson 7
What Is an Array?
Grade 2
Preparation
Lesson Narrative
In the first section of this unit, students determined whether a group of objects was odd or even by organizing them into pairs or putting them into 2 equal groups.
In this lesson, students describe the structure of an array. They describe the number of objects in each row of an array and learn that the total number of objects in an array can be determined by finding the sum of the number of objects in each row. Although students may describe many features of the arrays in the lesson, the focus is on describing the rows of the array. They attend to the number of rows, the number in each row, and the total number of objects. In the next lesson, students will be encouraged to describe the columns of an array and will use this term in future lessons.
- Engagement
None
- Comprehend (in spoken and written language) the term “row” refers to objects arranged side to side and the term “array” refers to an arrangement of objects into “rows” with an equal number of objects in “each row.”
- Create arrays and describe (orally) the rows of arrays.
- Let’s learn about arrays.
Required Preparation
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Create containers with 6, 7, and 9 counters for each group of 2.
Modify Activity 1, “What Is an Array?,” by taking the class on an outdoor walk around the school so students can collect natural objects from the ground, such as fallen leaves, seeds, acorns, pine cones, feathers, or pebbles. (Remind them to not pick fresh leaves or flowers.) They should choose one type of item and collect multiple, but do not tell them how many to collect. Instruct students to build arrays, but do not tell them how to build the arrays based on the number of items they chose. Ask students to share how they arranged their items into equal groups and why they chose to build that particular array.
When the activity is complete, remind students to leave the items in nature instead of taking them back to the classroom. Ask if they know why. (The items could feed a hungry animal. The items might be used as shelters by animals. Taking seeds out of nature means new plants won’t grow. If everybody took things out of nature, there would be nothing left.)
Environmental Principles & Concepts
Teacher Reflection Questions
In previous lessons, students explained why a number of objects was even or odd using diagrams and by skip-counting by 2. In this lesson, how did students use the structure of arrays to make sense of skip-counting and finding total amounts without counting by 1?