One Way Use a picture. Another Way Use fraction strips. Lesson 7.3

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1 Name Add Fractions Using Models Essential Question How can you add fractions with like denominators using models? Lesson 7.3 Numbers and Operations Fractions.NF.B.3d Also.MD.A.2 MATHEMATICAL PRACTICES MP2, MP3, MP Unlock the Problem Ms. Clark made a loaf of bread. She used _ of the bread for a snack and _ of the bread for lunch. How much did she use for a snack and lunch? One Way Use a picture. _ is _ eighth-size piece of bread. _ is _ eighth-size pieces of bread. Shade eighth-size piece. Then shade eighth-size pieces. snack lunch So, Ms. Clark used _ eighth-size pieces, or Think: The pieces you shaded represent the pieces Ms. Clark used. of the bread. Another Way Use fraction strips. The strip represents the whole loaf. Each _ part represents eighth-size piece of bread. Shade _. Then shade _. How many _ -size parts are shaded? _ Write the sum. _ + _ = Think: The model shows _ + _. So, Ms. Clark used _ of the bread.. Explain how the numerator of the sum is related to the fraction strip model. 2. Explain how the denominator of the sum is related to the fraction strip model. Math Talk MATHEMATICAL PRACTICES 2 Reason Abstractly Explain why _ + _. Chapter 7 397

2 Example Jacob needs two strips of wood to make masts for a miniature sailboat. One mast will be 3_ foot long. The other mast will be 2_ foot long. He has a strip of wood that is _ foot long. Is this strip of wood long enough to make both masts? Shade the model to show 3_ + 2_ Write the sum. 3_ + 2_ = Is the sum less than or greater than _? So, the strip of wood long enough to make both masts. 3. Explain how you used the number line to determine if the sum was less than _.. What if each mast was 2_ foot long? Could Jacob use the strip of wood to make both masts? Explain. Share and Show MATH BOARD N. Adrian s cat ate 3_ of a bag of cat treats in September and _ of the same bag of cat treats in October. What part of the bag of cat treats did Adrian s cat eat in both months? Use the model to find the sum 3_ + _. How many fifth-size pieces are shown? _ 3_ + _ = of a bag 3 39

3 Name Use the model to find the sum Find the sum. Use models to help. On Your Own Find the sum. Use models or i Tools to help. 7. _ + 2 _ = _ Math Talk = _. 3 _ + 3 _ =. _ + 2 _ =. _ 3 + _ 3 = MATHEMATICAL PRACTICES 3 Apply Explain how to add 2_ + 3_. _ + 2 _ =. 2_ + 2 _ = 9. _ + _ = 0. DEEPER Jason is making a fruit drink. He mixes 2_ quart of grape juice with 3_ quart of apple juice. Then he adds _ quart of lemonade. How much fruit drink does Jason make?. SMARTER A sum has five addends. Each addend is a unit fraction. The sum is. What are the addends? 2. SMARTER In a survey, 2 of the students chose Friday and 2 chose Saturday as their favorite day of the week. What fraction shows the students who chose Friday or Saturday as their favorite day? Shade the model to show your answer of the students chose Friday or Saturday. Chapter 7 Lesson 3 399

4 3. MATHEMATICAL PRACTICE Model Mathematics Jin is putting colored sand in a jar. She filled 2 0 of the jar with blue sand and 0 of the jar with pink sand. Describe one way to model the part of the jar filled with sand. Stained Glass Windows Have you ever seen a stained glass window in a building or home? Artists have been designing stained glass windows for hundreds of years. Help design the stained glass sail on the boat below. Materials color pencils Look at the eight triangles in the sail. Use the guide below to color the triangles: 2_ blue 3_ red 2_ orange _ yellow. MATHEMATICAL PRACTICE Write an Equation Write an equation that shows the fraction of triangles that are red or blue. WRITE Math Show Your Work. DEEPER What color is the greatest part of the sail? Write a fraction for that color. How do you know that fraction is greater than the other fractions? Explain. Image Credits: (c) PhotoDisc/Getty Images 00

5 Name Add Fractions Using Models Find the sum. Use fraction strips to help. 3_. 2 + = = Practice and Homework Lesson 7.3 COMMON CORE STANDARD.NF.B.3d Build fractions from unit fractions by applying and extending previous understandings of operations on whole numbers =. 2 + = =. + 2 = Problem Solving 7. Lola walks mile to her friend s house. Then 0 she walks mile to the store. How far does 0 she walk in all?. Evan eats _ of a pan of lasagna and his brother eats 2_ of it. What fraction of the pan of lasagna do they eat? 9. Jacqueline buys 2_ yard of green ribbon and _ yard of pink ribbon. How many yards of ribbon does she buy? 0. Shu mixes 2_ pound of peanuts with _ 3 3 pound of almonds. How many pounds of nuts does Shu mix?. WRITE Math Find a recipe in a book or online that includes the amount of salt as a fraction. Model how to find the amount of salt needed when the recipe is doubled. Chapter 7 0

6 Lesson Check (.NF.B.3d). Mary Jane has 3_ of a medium pizza left. Hector has 2_ of another medium pizza left. How much pizza do they have altogether? Use models to help. 2. Jeannie ate _ of an apple. Kelly ate 2_ of the apple. How much did they eat together? Use models to help. Spiral Review (.NBT.B.,.NBT.B.,.NF.A.) 3. Karen is making different kinds of greeting cards. She is making 2 of each kind. How many greeting cards is she making?. Jefferson works part time and earns $,20 in four weeks. How much does he earn each week?. By installing efficient water fixtures, the average American can reduce water use to about gallons of water per day. Using such water fixtures, about how many gallons of water would the average American use in December?. Collin is making a bulletin board and note center. He is using square cork tiles and square dry-erase tiles. One of every 3 squares will be a cork square. If he uses 2 squares for the center, how many will be cork squares? 02 FOR MORE PRACTICE GO TO THE Personal Math Trainer