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MODULE 4 Lesson 4 Objective •Add and subtract multiples of 10 and some ones within 100. Place Value • Say the number. • What digit is in the tens place? • What’s the value of the 7? 174 • State the value of the 1. • State the place of the 4. • Let’s try some more by asking the same questions. 258 734 860 902 Making a Ten Drill • 7 + ___ = 10 • Let’s find missing parts to make ten. If I say 7, you would say 3. • Ready? 7. • Say the number sentence. • Let’s try some more numbers: 4 23 3 27 7 42 13 17 48 58 Making the Next Ten to Add • When I say, 9+4, you say 10+3. • Ready? 9+4. • What’s the answer? • Let’s try some others: 19+4 9+6 8+3 8+5 7+6 7+4 29+4 19+6 18+3 18+5 17+6 17+4 49+4 29+6 48+3 88+5 27+6 67+4 79+4 59+6 Concept Development • There are 5 yellow cubes. How many • • • • linking cubes am I showing in this stick? How many in this stick? What is the difference between 8 and 5? What number sentence could I use to represent the difference between 8 and 5? 8–5=3. Concept Development Continued • Has the difference changed? • But what new number sentence can I use to represent the difference between my two sticks? • 9–6=3. • Is the difference still 3? • YES! Concept Development Continued • I add more to each bar. Did the • • • • • • difference change? Let’s test this idea. When we add the same amount to each number in a subtraction sentence, the difference stays the same. Now let’s try this with a new problem. 34 – 28 Now that is challenging! Try this one: 36 – 30. How did you know the answer so fast? Yes! Is it easier to subtract just tens! Concept Development Continued • Now, can you tell me how 34 – 28 and my other problem, 36 – 30, are related? Turn and talk. • Now how long is each bar? • We added 2 to each bar to make the problem easy! • Now it’s your turn. On your white board, solve these problems by making a tape diagram. Add on to both numbers to make the problem easier. 22-8 26-19 33-18 Concept Development Continued • There are 6 red cubes on one end • • • • and 4 red on the other end. How many yellows are in the middle? What is the total number of cubes? Let’s make 2 different addition sentences. What is the addition sentence for the total number of cubes? Now instead let’s join the 1 yellow with the 6 red. How do you know this is true 6+5 = 7+4? Concept Development Continued • Let’s use that same idea with • • • • • • larger numbers to make tens. Let’s solve 28 + 36. What does 28 need to be the next ten? What is 2 less than 36? How do you know this is true: 28+36=30+34? We can also show 2 more for 28 with our number bond. Let’s write both models in our journals and explain them to your partner. Concept Development Continued • Let’s do some more practice with the following problems: 19+35 36+29 78+24 37+46 Story Problem • Carlos bought 61 t-shirts. He gave 29 of them to his friends. How many tshirts does Carlos have left? • Solve! • Share!