MODULE 4Lesson 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? • State the value of the 1. • State the place of the 4. • Let’s try some more by asking the same questions.

174

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:

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• If 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

Story Problem

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

•Solve!•Share!