Mental Arithmetic: Using a Vending Machine Poster

Transcription

1 Mental Arithmetic: Using a Vending Machine Poster Objectives To review showing amounts of money with coins and to provide experiences with solving number stories involving addition of 2-digit numbers. epresentations etoolkit Algorithms Practice EM Facts Workshop Game Family Letters Assessment Management Common Core State Standards Curriculum Focal Points Interactive Teacher s Lesson Guide Teaching the Lesson Ongoing Learning & Practice Differentiation Options Key Concepts and Skills Count forward by 25s, 10s, and 5s. [Number and Numeration Goal 1] Show amounts of money using combinations of quarters, dimes, and nickels. [Operations and Computation Goal 2] Use a variety of strategies to add and subtract 2-digit numbers. [Operations and Computation Goal 2] Tell, write, and solve number stories. [Operations and Computation Goal ] Write addition and subtraction number sentences, using +, -, and =. [Patterns, Functions, and Algebra Goal 2] Key Activities Children show which coins they would use to purchase a single item from a vending machine. They show how much money they would need to purchase two or more items. They do a Buyer and Vendor activity. Ongoing Assessment: Recognizing Student Achievement Use Mental Math and Reflexes. [Number and Numeration Goal ] Materials Math Journal 2, pp. 19 and 19 Home Link 10 2 transparency of Math Masters, p. 25 (optional) tool-kit coins (at least 5 nickels, 10 dimes, and 2 quarters per child) base-10 blocks Advance Preparation Graphing and Analyzing Data Class Data Pad stick-on notes Children count the number of pencils in their desks. They use the collected data to create a bar graph and to determine data landmarks. Practicing with Fact Families Math Masters, p. 2 Children use fact triangles to practice with fact family extensions. Math Boxes Math Journal 2, p. 199 Children practice and maintain skills through Math Box problems. Home Link Math Masters, p. 2 Children practice and maintain skills through Home Link activities. READINESS Counting Coins per group: tool-kit coins, calculator Children practice counting mixed collections of coins. EXTRA PRACTICE Playing Coin-Dice per partnership: tool-kit coins, 2 dice Children practice making coin exchanges. Teacher s Reference Manual, Grades 1 pp Lesson

2 Getting Started Mental Math and Reflexes Dictate a pair of numbers. Have children write them on their slates with a space between the numbers. Then have children write <, >, or = in the space to compare them. 2, 2 < ; 5, < ; 9, 9 >, 9 < ; 10, 1 > ; 1, 1 = 90, 09 > ; 199, 229 < ; 55, 5 > Math Message A bag of sunflower seeds costs $0.0. Draw coin symbols to show one way to pay for them. Use, Í, and Â. Home Link 10 2 Follow-Up Briefly go over the answers. Ongoing Assessment: Recognizing Student Achievement Mental Math and Reflexes Use Mental Math and Reflexes to assess children s ability to compare numbers. Children are making adequate progress if they are able to compare the numbers in the first two sets of problems. Some children may be able to compare the numbers in the third set. [Number and Numeration Goal ] 1 Teaching the Lesson Math Message Follow-Up DISCUSSION Children share different ways to make 0 cents. Vending Machine Poster Using Coin Combinations to Make Purchases (Math Journal 2, p. 19; Math Masters, p. 25) $1.00 Ask children if they have ever bought food from a vending machine and, if so, how they knew how much each item cost. After children share their responses, display the overhead transparency of the Vending Machine Poster (Math Masters, page 25). Have children turn to the poster on journal page 19 to show how they would find the price of an item in the vending machine. Suggest or have children select an item to buy from the vending machine. Children use tool-kit coins to show the exact coins they would use to pay for the item. Repeat the activity as needed Push Open for Your Selection. Change Coin Return Adjusting the Activity Before beginning the activity, discuss all of the items on the Vending Machine Poster. Math Journal 2, p. 19 A U D I T O R Y K I N E S T H E T I C T A C T I L E V I S U A L 12 Unit 10 Year-End Review and Assessment

3 Adding 2-Digit Vending Machine Prices (Math Journal 2, p. 19) PROBLEM SOLVING Using the items and prices shown on the poster, model stories that involve two or more items. For example, I want to buy a granola bar and a bag of sunflower seeds. How much money do I need? Then ask children to create their own number stories. For each number story, children share and discuss their strategies. Encourage the use of mental arithmetic, coins, the number line, the number grid, or base-10 blocks to work out solutions. For at least one number story, have children model the prices using base-10 blocks. For instance, children may model the prices of the pretzels (5 ; or longs, 5 cubes) and the gum (25 ; or 2 longs, 5 cubes). Remind children to add tens to tens and ones to ones, composing a new 10 from the ones if necessary. Write number models and draw situation diagrams for selected problems. If children exhibit success with the addition problems, consider posing some 2-digit subtraction problems. For instance, ask children how much more the sunflower seeds cost than the granola bars. Remind children that they can count up (from 0 to 0 ) to subtract. NOTE Change the number of items and the prices as appropriate to keep interest high and the activity challenging. Doing a Buyer and Vendor Activity (Math Journal 2, pp. 19 and 19) PARTNER PROBLEM SOLVING Partners combine their tool-kit nickels, dimes, and quarters. If children are missing coins, supply additional coins from the class money supply. Partners take turns being the buyer and the vending machine. The buyer gives the vending machine the exact amount in coins to purchase an item. The vending machine determines if the coins equal the correct amount. Each buyer records his or her purchases in Problems 1 on journal page 19. Buying from the Vending Machine Pretend to buy items from the vending machine. Draw pictures or write the names of items you buy. Show the coins you use to pay for the items. Use Â, Í, and. Write the total cost Answers vary for Exercises 1... Show the cost of these items. Use Â, Í, and. Write the total cost. Sample answers: 5.. ÍÂ ÍÍÍÍÂ ÍÂ Í Total cost: $ Total cost: $ Math Journal 2, p. 19 Lesson

4 Name Fact Family Extensions Write the fact family for each Fact Triangle. Sample answers: = 0 - = - = =.. Teaching Master = - = - = 0-0 = 0 2 Ongoing Learning & Practice Graphing and Analyzing Data Ask children to record on stick-on notes how many pencils they have in their desks. Explain that they will use the information to make a bar graph showing the number of pencils in each child s desk. Children have seen and worked through many data routines this year. In this lesson, it is their turn to show you what they know. Scribe on the Class Data Pad as the class works together to create a bar graph. Guide children in determining what label should be on each axis and how to title the graph. Once the bar graph is complete, have children work with a partner or small group to determine the minimum, maximum, and middle values, as well as the range. Math Masters, p. 2 Practicing with Fact Families (Math Masters, p. 2) Use Math Masters, page 2 to provide practice with fact family extensions. Math Boxes (Math Journal 2, p. 199) Math Boxes 1. Record the times. Children Measure the line segment. It is about First-Grade Bedtimes :0 :00 :0 9:00 9:0 P.M. Earliest bedtime: Latest bedtime: 2 :0 9:0 Range: hours 5 inches long. 2. Clay has Á ÍÍÍ. Rosa has. Who has more money? Rosa How much more money? 20. Circle the bigger fraction. Mixed Practice Math Boxes in this lesson are paired with Math Boxes in Lesson Writing/Reasoning Have children draw, write, or verbalize an answer to the following question: How do you add 10 to a number? A reasonable answer should explain an addition strategy such as using base-10 blocks, the number grid, or counting on. Home Link (Math Masters, p. 2) Home Connection Children use pictures to solve number stories. Fill in the circle next to the best answer. A. 9 B. C. 1_ 2 D. 1_ Fill in the missing numbers in Rule +10 out in out Math Journal 2, p How many sides? sides How many corners? corners Unit 10 Year-End Review and Assessment

5 Home Link Master Differentiation Options READINESS Counting Coins SMALL-GROUP 5 15 Min Name HOME LINK Solving Number Stories Family Note 25 Ask your child to explain what he or she did to solve Problems 1 and 2 below. Your child may want to model the problems with coins. Please return this Home Link to school tomorrow. 5 FRUIT BAR To provide experience counting combinations of coins, have children count collections of quarters, dimes, and nickels and then find the total of all of the coins. Children take a small, random handful of tool-kit coins. They separate the coins into groups of quarters, dimes, and nickels and then find and record on a half-sheet of paper a total for each group of coins. Children then find the total of all of the coins and record on the half-sheet of paper a number sentence for the grand total. Encourage children to use calculator counts to check their totals. EXTRA PRACTICE Playing Coin-Dice PARTNER 5 15 Min For each problem, use Î, Â, Í,, or Á to show the amount you pay. 1. You want to buy a and a. How much will you pay? 2. You want to buy a and a. How much will you pay? Show the amount in two different ways. Practice Write the missing numbers. Sample answers: ÍÍ FRUIT BAR Á = +. + = = Math Masters, p. 2 Children practice making coin exchanges by playing Coin-Dice. Add quarters if appropriate for children. For detailed instructions, see Lesson -12. Planning Ahead For the optional Enrichment activity in Part of Lesson 10-, you will need a collection of advertisements from magazines, catalogs, and newspapers showing prices that are appropriate for children s computational skills. Lesson 15