MODULE 4Lesson 4

Objective

•Add and subtract multiples of 10 and some ones within 100.

•Solve one- and two-step word problems within 100 using strategies based on place value.

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:

23 27 42 48 58

4 3 7 17 13

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 8+5

48+3

18+3

8+3

59+6

29+6

19+6

9+6

79+4

49+4

29+4

67+4

17+4

7+4

27+6

17+6

7+6

88+5

18+5

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

37+4678+24

36+29

Application Problem

•Carlos bought 61 t-shirts. He gave 29 of them to his friends. How many t-shirts does Carlos have left?

•Solve!•Share!

Rename the Units: Choral Response

• I’m going to give you some number of ones. I want you to pull out as many tens as you can, and then tell me how many tens and ones. If there are no ones, only say the tens. Ready?

• Say this number sentence.

10 ones = ____ ten.

20 ones = ____ tens. 63 ones.

75 ones. 70 ones.

60 ones. 23 ones.

97 ones. 90 ones. 79 ones.

Concept Development(NOTE: Invite two pairs of students who you think can successfully model the problem to work at the board while the others work independently or in pairs at their seats. After two minutes, have the two pairs of students share only their labeled diagrams. For about one minute, encourage the demonstrating students to respond to feedback and questions from their peers.)

• Let’s review some questions we should ask to solve a story problem: • First ask, “Can you draw something?”• Then think, “What can you draw?”• Finally, “What conclusions can you make from your

drawing?”

Problem 1Directions: Solve a single-step word problem using a tape diagram and the Arrow way.

•Don has 34 brownies. He bakes 22 more. How many brownies does he have now?

Problem 2Directions: Solve a single-step word problem by drawing a tape diagram and using a number bond or the Arrow way to solve.

• Sam has 46 red apples and some green apples. He has a total of 88 apples. How many green apples does he have?

Problem 3Directions: Solve a two-step problem by drawing a tape diagram and using a number bond to solve.

• There are 31 students on the red bus. There are 29 more students on the yellow bus than on the red bus. How many students are on the yellow bus?

• How many students are on both buses combined?

Problem 4Directions: Solve a two-step problem by drawing a tape diagram and using the Arrow way to solve. • Ms. Lopez cut 46 cm of yarn. Ms. Hamilton cut 22 cm fewer than Ms. Lopez. How many centimeters of yarn did Ms. Hamilton cut?

• How many centimetersof yarn did they have altogether?

Problem Set

Exit Ticket• Here is homework

for tonight