AnnouncementsSlide 2Let’s add in AlphabitiaYou try:Let’s subtractYou Try…You try: Use manipulatives or drawings to explainExploration 3.1Begin AdditionVocabularyAddition and Place ValueMental ArithmeticSlide 13The name of the method is not importantYou try…EstimationYou will have 5 secondsSlide 18Slide 19Estimation vs. Exact AnswerRoundingA problem:Explain the mathSlide 24Explain why the child made the mistakeAssignmentAnnouncements•Last day to drop without a W is 12 February•First exam: 13 February•Class Notes in the Bookstore. Need by 19 February. Cost is $3.50.What is wrong with saying 372 What is wrong with saying 372 base 6base 6? ? What is a proper way of writing this What is a proper way of writing this number in base 6?number in base 6?Let’s add in Alphabitia BCD+ DBBCD is DB is BCD + DB isYou try: B0B+ABCUse the manipulatives or draw pictures to help explain your answer.Let’s subtract CBD- ADC = CBD is ADC is CBD - ADC isYou Try… D00-B0B B0A-BDYou try: Use manipulatives or drawings to explain BBC - A0C A0A0D - BCAExploration 3.1•In your groups: Do Part 1, #1 and #2a •Then do Part 2, #1 and 2Begin Addition•Ways to represent addition:•1. Counters •2. Number Line •3. Part-Part Wholeabc 0 2 4 6 8 10Vocabulary•A + B = C•A and B are called Addends•C is called the Sum•Since A + B = B + A every time, we give it a special name: commutative property.•Since A + (B + C) = (A + B) + C every time, we give it a special name: associative property.Addition and Place Value•If we have 154 + 69Mental Arithmetic•39 + 57Mental Arithmetic•39 + 57•Leading digit (30 + 50) + (9 + 7)•Compensation (40 - 1) + 57•Compensation (40 + 57) - 1•Break and Bridge (39 + 50) + 7•Compatible Numbers (39 + 51) + 6The name of the method is not important•Put down your pencil•68 + 74•How did you do this?•How might children do this?You try…•23 + 96•489 + 723Estimation•Get a QUICK answer that is close but not exact!You will have 5 seconds•382 - 147Estimation•382 - 147•Actual answer: 235•Ways to estimate:•380 - 150 = 230•400 - 150 - 20 = 230•375 - 150 = 225•385 - 145 = 240•390 - 140 = 250You try:•45 + 87•391 + 1472Estimation vs. Exact Answer•Are the exact values of the addends given?•Is the exact value of the sum required?•In general: changing values (like population), measurement values (like distance), and predictions (like 35% chance of rain) are estimatesRounding•When you estimate, you are rounding to the nearest ten, hundred, million, etc.•If you round up, you are making an overestimation.•If you round down, you are making an underestimation.A problem:•I am thinking of 3 numbers whose sum is greater than 70.•Look at each statement below. Mark it as true or false. Be ready to explain why.•All three numbers are greater than 20.•If two of the number are less than 20, the other must be greater than 20.Explain the math• 348+ 472 10 11 7• 820Explain the math• 471+ 299 10 160 600• 770•How is this different from the previous problem?Explain why the child made the mistake•341 + 287 is the same as 340 + 290 + 7 + 3•749 + 684 is the same as 700 + 600 + 49 + 1 + 84 + 16 •322 + 468 is the same as 320 + 460•Would the mistake have been made if manipulatives had been used? Explain.Assignment•Section 3.1 p. 150-151#5, 6, 10,