Divide by Multiples of 10

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Vincent Gregory
6 years ago
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1 Objective Divide by Multiples of 10 Once students have explored division by multiples of 10 visually, they can learn the process of solving

This idea, however, is too abstract without a student being able to see the division process modeled in a concrete way.

In this lesson, students will use Base Ten Blocks to solve division problems with multiples of 10. Common Core State Standards 4.NBT.

How many rods and units were in each group? Ask: How many groups did you make for the second problem, 220 20? How many were in each group?

Ask: Can you think of a rule to use when you are dividing and both numbers are multiples of 10? Does this rule make dividing big numbers easier?

Have students write a sentence telling how they solved the problem and draw a picture to show the number of rows in the auditorium.

Give groups 100 to 200 cubes and have them practice dividing the total by different multiples of 10, such as 20, 30, and 40.

1 1 Objective Divide by Multiples of 10 Once students have explored division by multiples of 10 visually, they can learn the process of solving the algorithm through simplifying. This idea, however, is too abstract without a student being able to see the division process modeled in a concrete way. It is important for students to experience the concept before moving to paper and pencil. In this lesson, students will use Base Ten Blocks to solve division problems with multiples of 10. Common Core State Standards 4.NBT.1 38 Talk About It Discuss the Try It! activity. Ask: How many groups of Base Ten rods and units did you make for the first problem, 22 2? How many rods and units were in each group? Ask: How many groups did you make for the second problem, ? How many were in each group? Ask: What do you multiply 22 by to get 220? What do you multiply 2 by to get 20? Tell students that these numbers are called multiples of 10. Ask: Can you think of a rule to use when you are dividing and both numbers are multiples of 10? Does this rule make dividing big numbers easier? How? Solve It With students, reread the problem. Have students write a sentence telling how they solved the problem and draw a picture to show the number of rows in the auditorium. More Ideas For other ways to teach about dividing by multiples of 10 Have students use Centimeter Cubes to model dividing by multiples of 10. Give groups 100 to 200 cubes and have them practice dividing the total by different multiples of 10, such as 20, 30, and 40. Remind students that it s OK to have a remainder. Write , , and on the board. Have students use Base Ten Blocks to solve the problems. For an extra challenge, have students work on problems with four-digit dividends, such as 1,200 30; 1,500 50; and so on. Formative Assessment Have students try the following problem. Andy wants to give away his basketball cards to his friends. He has 10 friends and 200 cards. How many cards will each friend get? A. 2 B. 10 C. 12 D. 20

Try It! 20 minutes Groups of 4 Here is a problem about dividing by multiples of 10. An auditorium in the school holds 220 people in all.

Distribute Base Ten Base Ten Blocks (2 flats, 30 rods, Blocks to groups of students.

Students should notice that the numbers in the problems are similar except for the number of zeros they contain.

Have students use 2 rods and 2 units to model 22. Then have them divide the blocks into 2 equal groups. Write the answer, 11, on the board. 2. Now have students use flats and rods to build 220.

They should then exchange the remaining 2 rods for 20 units and place 1 unit with each rod. 3.

Have students check their answers using multiplication.

2 Try It! 20 minutes Groups of 4 Here is a problem about dividing by multiples of 10. An auditorium in the school holds 220 people in all. Each row has 20 seats. How many rows are there in all? Introduce the problem. Then have students do the Materials activity to solve the problem. Distribute Base Ten Base Ten Blocks (2 flats, 30 rods, Blocks to groups of students. Write the division and 30 units per group) sentences 22 2 and on the board. Students should notice that the numbers in the problems are similar except for the number of zeros they contain. Remind students of the pattern they see when multiplying 22 1, 22 10, , and so on. 1. Say: First, let s divide 22 by 2. Have students use 2 rods and 2 units to model 22. Then have them divide the blocks into 2 equal groups. Write the answer, 11, on the board. 2. Now have students use flats and rods to build 220. Say: We need to divide 220 into 20 equal groups. Students should exchange each flat for 10 rods and make 20 groups of 1 rod each. They should then exchange the remaining 2 rods for 20 units and place 1 unit with each rod. 3. Write the answer for the second problem, 11, on the board. Ask: What do you notice about the answers you got for the two problems? Have students check their answers using multiplication. Watch for students who count the number of groups instead of the number of rods and units in each group. Have students go back and reread the question and check to see if their answer makes sense. Also, watch for students who conclude that they can remove common last digits in all division problems, thinking for example that is the same as Have students work out problems like these to discover that they will get two different answers. 39

3 Lesson 1 Name Answer Key Use Base Ten Blocks to model the division sentence and the sentence for the related division by a multiple of 10. Write each division problem. (Check students work.) 1. = = Using Base Ten Blocks, model each division problem. Then sketch your model for the division by a multiple of 10. Write each division sentence. (Check students models.) = = = = 8 Find each quotient = = = = = = 40 Download student pages at hand2mind.com/hosstudent.

4 Answer Name Key Challenge! Explain why you can use a simpler problem to find the quotient when both the dividend and the divisor are multiples of 10. Challenge: (Sample) You can cross out the 0 in both the dividend and the divisor because when you divide both numbers by 10 it does not change the answer. Download student pages at hand2mind.com/hosstudent. 41

Lesson 1 Name Use Base Ten Blocks to model the division sentence and the sentence for the related division by a multiple of 10. Write each division problem. 1. = = Using Base Ten Blocks, model each division problem.

5 Lesson 1 Name Use Base Ten Blocks to model the division sentence and the sentence for the related division by a multiple of 10. Write each division problem. 1. = = Using Base Ten Blocks, model each division problem. Then sketch your model for the division by a multiple of 10. Write each division sentence = 30 = = 40 = Find each quotient = = = = = = 40

6 Name Challenge! Explain why you can use a simpler problem to find the quotient when both the dividend and the divisor are multiples of

Talk About It. More Ideas. Formative Assessment. Have students try the following problem.

Talk About It. More Ideas. Formative Assessment. Have students try the following problem. 5.NF. 5.NF.2 Objective Common Core State Standards Add Fractions with Unlike Denominators Students build on their knowledge of fractions as they use models to add fractions with unlike denominators. They