4.2. Divide Decimals by Whole Numbers. Investigate. Draw Conclusions. Math Talk. Essential Question. Materials decimal models color pencils

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1 ? Name Number and 4.2 Operations 5.3.F MATHEMATICAL PROCESSES 5.1.C, 5.1.G Essential Question Divide Decimals by Whole Numbers How can you use a model to divide a decimal by a whole number? Investigate Hands On Materials decimal models color pencils Angela has enough wood to make a picture frame with a perimeter of 2.4 meters. She wants the frame to be a square. What will be the length of each side of the frame? A. Shade decimal models to show 2.4. B. You need to share your model among _ equal groups. C. Since 2 wholes cannot be shared among 4 groups without regrouping, cut your model apart to show the tenths. There are _ tenths in 2.4. Share the tenths equally among the 4 groups. There are _ ones and _ tenths in each group. Write a decimal for the amount in each group. _ D. Use your model to complete the number sentence = _ So, the length of each side of the frame will be _ meter. Draw Conclusions 1. You can also use area models to represent division. Shade the area model below and circle groups to show Math Talk Mathematical Processes What other manipulatives or models could you use to solve this problem? Module 4 161

2 Make Connections You can also use base-ten blocks to model division of a decimal by a whole number. Hands On Materials base-ten blocks Kyle has a roll of ribbon 3.21 yards long. He cuts the ribbon into 3 equal lengths. How long is each piece of ribbon? Divide STEP 1 Use base-ten blocks to show Remember that a flat represents one, a long represents one tenth, and a small cube represents one hundredth. There are _ one(s), _ tenth(s), and _ hundredth(s). STEP 2 Share the ones. Share an equal number of ones among 3 groups. There is _ one(s) shared in each group and _ one(s) left over. STEP 3 Share the tenths. Two tenths cannot be shared among 3 groups without regrouping. Regroup the tenths by replacing them with hundredths. There are _ tenth(s) shared in each group and _ tenth(s) left over. There are now _ hundredth(s). STEP 4 Share the hundredths. Share the 21 hundredths equally among the 3 groups. There are _ hundredth(s) shared in each group and _ hundredth(s) left over. So, each piece of ribbon is yards long. 162 Math Talk Mathematical Processes Explain why your answer makes sense.

3 Name Share and Show Use the model to complete the number sentence = = Problem Solving 3. What's the Error? Aida is making banners from a roll of paper that is 4.05 meters long. She will cut the paper into 3 equal lengths. She uses base-ten blocks to model how long each piece will be. Describe Aida's error. 4. Multi-Step Sam can ride his bike 4.5 kilometers in 9 minutes, and Amanda can ride her bike 3.6 kilometers in 6 minutes. Which rider might go farther in 1 minute? 5. Explain how you can use inverse operations to find Module 4 Lesson 2 163

4 Daily Assessment Task Mathematical Processes Fill in the bubble completely to show your answer. 6. Multi-Step Yesterday, a bamboo plant was yards tall. Today, the bamboo had grown by 0.34 yard. Bryson chopped the bamboo into 6 equal pieces. How long was each piece? A 21.6 yd C 2.16 yd B yd D 216 yd 7. Representations Terrance used base-ten blocks to help him divide a decimal by 4. His model is shown. What division problem did he model? A B C D Multi-Step Marvyn worked for 3 days. He earned $87.20 each day. He uses his earnings to buy four chairs. If he has no money left over, what is the cost of each chair? A $65.40 C $ B $ D $21.80 TEXAS Test Prep 9. A bag of oranges costs $7.65. Five friends want to share the bag. How much will each friend pay? 164 A $38.25 C $2.00 B $1.53 D $1.13

5 Homework and Practice Name Number and Operations 5.3.F MATHEMATICAL PROCESSES 5.1.C, 5.1.D 4.2 Divide Decimals by Whole Numbers Use the model to complete the number sentence = = = = 5. Explain how you can use the whole number expression to check that your answer to Exercise 2 is reasonable. Problem Solving 6. Mrs. Tillman builds furniture. She saws a maple board that is 4.56 meters long into 4 equal lengths. She saws an oak board that is 3.69 meters long into 3 equal lengths. Which is longer, a piece of oak or a piece of maple? Explain. 7. Drew has a video game with five different challenges. He sets the timer to play his game for minutes. He spends the same amount of time playing each challenge. How long does Drew play the fifth challenge? Module 4 Lesson 2 165

6 Lesson Check TEXAS Test Prep Fill in the bubble completely to show your answer. 8. Karina places concrete blocks along one side of her garden. The length of the border is 3.6 meters. If she uses 9 concrete blocks, what is the length of 1 block? A B C D 0.3 meter 0.9 meter 0.04 meter 0.4 meter 9. Max used base-ten blocks to solve the division problem Which set of blocks shows the quotient for ? A B C D 4 ones, 5 tenths, 0 hundredths 4 ones, 0 tenths, 5 hundredths 0 ones, 4 tenths, 5 hundredths 5 ones, 0 tenths, 4 hundredths 10. The base-ten blocks pictured below show Carter s solution to a division expression. 11. Mr. Jefferson gives his two children $5.46 to spend at the garage sale. If they split the money evenly, how much will each child have to spend? A $1.82 B $1.23 Which expression did Carter solve? A C $2.23 D $2.73 B C D Multi-Step Mrs. Gonzales decorates the perimeter of her rectangular bulletin board with ribbon. She cuts a ribbon 3.72 yards long in half to decorate the top and the bottom. She cuts a ribbon 2.6 yards long in half to decorate the two sides. How much shorter is one side ribbon than the top ribbon? 166 A B C D 0.56 yard 0.5 yard 0.66 yard 0.6 yard 13. Multi-Step Tamika bought 6 fish at the pet store for a total of $7.26. If two of the fish together cost $4.10, and each of the other four fish had the same cost, how much was each remaining fish? A $1.21 B $2.05 C $0.79 D $3.16