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Up, Up, and Array
Students will be able to describe an array using repeated addition.
- Give each student 25 counters.
- Ask your students to make eight groups with three 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 five-by-five 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 four rows and five 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 five rows and four 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(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.
- 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.