Up, Up, and Array
Students will be able to describe an array using repeated addition.
Introduction (5 minutes)
- Give each student 25 counters.
- Ask your students to make 8 groups with 3 counters in each group.
- Direct your students to count by threes.
- Ask them to identify how many counters there are altogether.
- Write an equation to show this. For example: 3 + 3 + 3 + 3 + 3 + 3 + 3 + 3.
- Tell students that today they are going to describe an array, or an ordered display, using number sentences.
Explicit Instruction/Teacher Modeling (10 minutes)
- Draw a 5-by-5 array on the board.
- Read aloud the following problem: Maria has 4 treat bags with 5 cookies in each bag. How many cookies are there in all?
- Model the problem by shading in 4 rows and 5 columns on the board.
- Ask students what strategy they could use to find the total number of cookies.
- Ask students if the answer would change if the numbers were turned around (if there were 5 rows and 4 columns). Explain that this does not change the answer.
- Give students a problem such as: Tiki has 4 rows of cars with 2 cars in each row. How many cars are there?
- Model the problem on the board by drawing it out.
- Use repeated addition to write a number sentence.
Guided Practice/Interactive Modeling (10 minutes)
- Draw other arrays on the board, and have students use counters to practice solving and writing addition sentences for each array.
Independent Working Time (10 minutes)
- Have students complete the Array Practice worksheet on their own.
- Enrichment: Give advanced students 35 counters. Have them create as many different arrays as they can with all 35 counters. Then, have them write number sentences for each array.
- Support: Give students manipulatives to complete their arrays.
Assessment (5 minutes)
- Have students answer the following problem: There are 4 rows of chairs with 6 chairs in each row. How many chairs are there in all?
- Circulate and observe students as they work.
Review and Closing (5 minutes)
- Ask a volunteer what an array is.
- Have students provide real-life examples of arrays, such as bookshelves and egg cartons.
- Watch the Real Life Arrays video.