EXT K-2 Sampler

20 39 ©Math TeachersPress, Inc.,Reproduction by anymeans is strictly prohibited. TENS ONES 62 – 38 TENS ONES First build the larger number. Then remove the smaller number. TENS ONES Now, you can remove 8 ones and 3 tens. Record the problem this way. 62 – 38 24 1. 54 – 26 5. 73 – 17 2. 83 – 18 6. 80 – 27 3. 94 – 21 7. 56 – 38 4. 60 – 16 8. 74 – 35 9. Fred’s book has 85 pages. He read 38 pages. How many pages does he have left to read? __________ 11. 10. Marco’s book has 72 pages. Sally’s book has 86 pages. Howmanymore pages are there in Sally’s book? __________ SubtractionwithRegrouping There are not enough ones… Exchange 1 ten for 10 ones. You are reading amystery book with 62 pages.You have read 38 pages. Howmany pages do you have left to read? Jake subtracted 62–25 and got the answer 43.Explain inwords, pictures, andwriting if Jake’s answer is correct or incorrect. DISCUSSION Solve. Show the regrouping. 28 65 73 44 56 53 18 39 47pages 14pages 7 5 6 4 7 6 13 10 14 16 10 13 39 Objective48: To subtract 2-digit numberswith and without regrouping. Touse the shortcut for recording theproblem. Materials: PlaceValueMat (Master 10), base tenblocks, red andgreen crayons (optional) SubtractiononaPlaceValueMat Each student shouldhavebase tenblocks and aPlace ValueMat.Write2problems on theboard and ask students tomakeup awordproblem tomatch. 32 43 –14 –15 Read subtractionproblemswrittenby the class. For eachproblem, have studentsusebase tenblocks on aPlace ValueMat and record theirworkwithpaper andpencil. Ask avolunteer to explainwhat shedidwith theblocks for each step. Record the informationon theboard as the student explains each action. Showhow to record the problems. Provide continuedpracticeon thisdifficult algorithm throughout the term. What is thepattern for subtracting2-digit numbers? (Study thedigits in theones place to see if the topdigit is greater than thebottom digit. If not, trade1of the tens for 10ones so there are enoughones to subtract. Then subtract the tensdigits.) Each student shouldhavebase tenblocks and aPlace ValueMat. Read the story at the topof thepage. Review the action. (taking anumber apart or subtraction) Useyourblocks to find theanswer. Have avolunteer explainhow sheused theblocks to find the answer.Work through each stepof the example together. Have studentswork inpairs to complete the first row withblocks. Writean“R”above theproblems thatwill require regrouping in the first row. Howdoyouknow if theproblem requires regrouping? (if theones-placedigit in the topnumber is smaller than theones-placedigit in thebottomnumber, thenyoumust regroup) Remediation Studentsmayuse crayons to showwhether aproblem requires regrouping. They can color theones digit in the minuend (the largernumber) green if no regrouping is required. They can color it red if regrouping is required. Checkwork carefully. A clue tohelp students remember to renamenumbers before subtracting is the threeBs:When theBottom number isBigger, youBorrow. Write “BBB”on a sign andplace it in the classroom. Remember to study theproblem first to see if itwill need regrouping. Assessment Each student shouldhavebase tenblocks and aPlace ValueMat. Present theseproblems: 72 53 – 28 – 31 Showmehow to solve theproblem.Tellmewhat you aredoingwith theblocks. Showmehowyou record the problem.What is thepattern? (Subtract theones. If you needmoreones tobe able to subtract, regroupor trade 1 ten for 10ones. Subtract the tens from thenumber of tens left after the trade.) FamilyMathActivity SendSkill Builder 48-2homewith students tobeused as a familymath activity. Skill Builders 48-3, 48-4 Lesson 12, 2ETeacherGuide 2.OA.1, 2.NBT.5, 2.NBT.9 LessonPlanPage PD Step5 ProfessionalDevelopment inEveryLesson The LessonPlan sectionof theTeacherManual contains everything the teacher needs to doand say for each lesson . TheC–R–Amodel is implemented inevery lesson. 1. Starting the Lesson Each lesson states the learningobjec- tives,materialsneeded, and themath vocabularywords. Select lessonsmay also includea children’s story. 2. Realworldproblems and childrens stories areusedas a vehicle for intro- ducingmath concepts. This section presents themath concept at the concrete stageof learning. Anactive, hands-onapproachwith trueman- ipulativesdevelopsunderstandingof the concept. Lessons are lightly scripted inbold type to support the teacher. Key ideas for teachers to say. 3. Pictures at the topof thepage linkhands-onactivity topracticeat theabstract stage. Thought bubbles support andguide standard thinking. 4. Additional instructional support is provided in the formof games, a class file forwritingwordproblems, and suggested skill-buildingexercises of reproduciblematerials from the Masters andSkill Builders section of theTeacherManual. Games. Students strengthen their problem-solving skills as theyapply themath concept used ineachgame. Skill-BuildingPractice. Many lessons include follow-uppractice to support the lessonandprovideadditional differentiated instruction for ELL and students with special needs. Objectives for CCSS, CCSS-CA, andTEKSnotedon lessonplans in respectiveTeacherManuals. Professional Development icon alert indicates avideo lesson. Available ineGuide.