Guro Ako - Teacher Talks



Lesson 31: Rounding Decimal Numbers to the Nearest Hundredths and Thousandths Week 1Objective: Rounds decimal numbers to the nearest hundredths and thousandths.Value Focus: SportsmanshipPrerequisite Concepts and Skills:Distinguishing the different place values of decimals.Reading and writing decimal numbers.Materials: flashcards, number lineReferences: K to 12 Grade 5 Curriculum (MN5S-IIa-1012.3) p.57, Lesson Guide in Mathematics Grade 5 pp. 316-318, Growing Up with Math pp. 170-171, Math for Life pp.215-217Instructional Procedure:A. Preliminary Activities 1. Drilla) Call 21 volunteer pupils and group them into 3. b) Provide each group with number cards from 0 to 5 and a decimal point.534120. Ex. c) Each group will form the number given by the teacher. ExampleI am a 5-digit number. My tenths is twice my hundredths digit, and my one’s digit is the sum of my tenths and ten thousandths digit. My thousandths digit My thousandths digi is a place value holder. (5.4201)d. The first group to form the number correctly wins the game.* Valuing: Who do you think will offer the first handshake after the game? Why? If you were the winner/loser in a game, what will you do?2. Review: Relay GameWrite the decimals that the teacher will dictate.Mechanics:a. The teacher dictate the decimal number.b. The first pupil in a row will write his answer on a piece of paper as a group’s answer sheet.c. He pass it to his teammate next to him for his answer to the number dictate bythe teacher.d. As soon as the last pupil in a row has written his answer he submits their answer sheet to the teacher for checking.e. The group with the most number of correct answers win.3. Motivation:What percent is the molecules of carbon dioxide present in the earth’s atmosphere?B. Developmental Activities1.PresentationPresent the problem in the class.“Of the 100% total molecules present in the total molecules present composition of the Earth’s atmosphere, only 0.0325 percent is carbon dioxide.’Ask: What number is closest to 0.0325? Why? Why not? What are the other possible numbers closest to 0.325? What are the rules in rounding off decimal numbers? 2. Performing the ActivityA. Encourage the pupils to work in pairs. Give them time to solve for the answer to the problem by illustration.Solution 1: By using the number line131885733 0.323 0.324 0.325 0.326 0.327 0.328 0.329 0.330 0.331 0.332 0.333From the diagram, it is easy to see that 0.325 is closest to 0.330.325 rounded to nearest hundredths is 0.33It means it rounds up. Solution 2 By following the rules in rounding off numbers.0. 3 2 5 Round off place ( hundredths digit)The digit o the right is 5, so it is round up.0.325 rounded to the nearest hundredths 0.33 B. Have the pupils play by pair. The pair that gets the most number of correct answers wins.1. Flash cards one at a time. Let the pupils round to nearest hundredths.75.34600.04520.38927.3466.5402. Flash the cards one at a time. Let the pupils round to the nearest thousandths.12.4093532.34876.14696.3457122.786493. Processing the ActivityAfter the group have played, ask,” How do you find the activity? How did you round decimal number nearest to hundredths and thousandths?”Expected answer:By using number lineBy following the rules in rounding off numbers.4. Reinforcing the Concept and SkillsDiscuss the presentation on Explore and Discover and the other examples, LM Math Grade 5. Check their answer. For mastery, have them answer the answer theItems under Keep Moving on page _____ of LM Math Grade 5. Check pupils answers.5. Summarizing the LessonWhat is the rule to be followed when rounding decimals? 1. Identify the digit to be rounded-off.2. Inspect the digit to the right of the required place. a. If the digit is greater than 5, add 1 to the digit at the required place. b. If the digit is less than 5, retain the digit at the required place. Then drop all the digits to the right of the required place. c. Copy all the digits to the left of the required place if there are any.6. Applying to New and Other SituationsAsk the pupils to do the activity under Apply Your Skills, LM Math Grade 5.C. AssessmentRound off the following to the nearest place indicated.HundredthsThousandths1. 0.8236.58642. 1.37635.04653. 0.93774.30914. 0.60849.17195. 0.38135.0007D. Home ActivityRemediationComplete the table.Round toDecimalsHundredthsThousandthsTen Thousandths1. 0.894322. 5. 099683. 2.964254. 5.23585. 0.86302EnrichmentRound 85.81267 to the nearest place indicated.a. hundredthsb. thousandths ................
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